@article {2461,
	title = {Direct Measurement of the Kinetics of CBM9 Fusion-Tag Bioprocessing Using Luminescence Resonance Energy Transfer},
	journal = {Biotechnology Progress},
	volume = {25},
	number = {3},
	year = {2009},
	note = {ISI Document Delivery No.: 462SETimes Cited: 1Cited Reference Count: 44Kavoosi, Mojgan Creagh, A. Louise Turner, Robin F. B. Kilburn, Douglas G. Haynes, Charles A.},
	month = {May-Jun},
	pages = {874-881},
	type = {Article},
	abstract = {The economics of affinity-tagging technologies, particularly at preparative scales, depends in part on the cost and efficiency of the bioprocessing step used to remove the affinity tag and obtain the final purified product (Lowe et al., J Biochem Biophys Methods. 2001,49:561-574). When CBM9, the family 9 cellulose binding module from Thermotoga maritima, serves as the affinity tag, the overall efficiency of tag removal is a function of the choice of processing enzyme and the local structure of the cleavage site, most notably the linker sequence flanking the bioprocessing recognition site on the tag side. A novel spectroscopic method is reported and used to rapidly and accurately measure CBM9 fusion-tag bioprocessing kinetics and their dependence on the choice of linker sequence. The assay monitors energy transfer between a lanthanide-based donor bound to the CBM9 tag and an acceptor fluorophore presented on the tat-get protein or peptide. Enzyme-catalyzed cleavage of the fusion tag terminates this resonance energy transfer, resulting in a change in fluorescence intensity that can be monitored to quantify substrate concentration over time. The assay is simple, fast and accurate, providing k(cat)/K-M values that contain standard errors of less than 3\%. As a result, both substantial and subtle differences in bioprocessing kinetics can be measured and used to guide bioproduct design. (C) 2009 American Institute of Chemical Engineers Biotechnol. Prog., 25: 874-881, 2009},
	keywords = {10A, ACTIVE-SITE, affinity chromatography, BEND ANGLE, CARBOHYDRATE-BINDING MODULE, CONFORMATIONAL-CHANGES, enterokinase, ESCHERICHIA-COLI, fusion tag, green fluorescent protein (GFP), high throughput assay, LANTHANIDE, library, linker, luminescence, protein purification, PURIFICATION, RECOMBINANT PROTEINS, resonance energy transfer (LRET), RNA-POLYMERASE, terbium, THERMOTOGA-MARITIMA, XYLANASE},
	isbn = {8756-7938},
	url = {<Go to ISI>://000267375500030},
	author = {Kavoosi, M. and Creagh, A. L. and Turner, R. F. B. and Kilburn, D. G. and Haynes, C. A.}
}
@article {2120,
	title = {Identification and structural characterization of a CBP/p300-binding domain from the ETS family transcription factor GABP alpha},
	journal = {Journal of Molecular Biology},
	volume = {377},
	number = {3},
	year = {2008},
	note = {ISI Document Delivery No.: 293ZPTimes Cited: 5Cited Reference Count: 60Kang, Hyun-Seo Nelson, Mary L. Mackereth, Cameron D. Scharpf, Manuela Graves, Barbara J. McIntosh, Lawrence P.},
	month = {Mar},
	pages = {636-646},
	type = {Article},
	abstract = {Using NMR spectroscopy, we identified and characterized a previously unrecognized structured domain near the N-terminus (residues 35-121) of the ETS family transcription factor GABP alpha. The monomeric domain folds as a five-stranded beta-sheet crossed by a distorted helix. Although globally resembling ubiquitin, the GABP(x fragment differs in its secondary structure topology and thus appears to represent a new protein fold that we term the OST (On-SighT) domain. The surface of the GABP alpha OST domain contains two predominant clusters of negatively-charged residues suggestive of electrostatically driven interactions with positively-charged partner proteins. Following a best-candidate approach to identify such a partner, we demonstrated through NMR-monitored titrations and glutathione S-transferase pulldown assays that the OST domain binds to the CH1 and CH3 domains of the co-activator histone acetyltransferase CBP/p300. This provides a direct structural link between GABP and a central component of the transcriptional machinery. (C) 2008 Elsevier Ltd. All rights reserved.},
	keywords = {BACKBONE DYNAMICS, C-13-LABELED PROTEINS, CREB-BINDING-PROTEIN, ESCHERICHIA-COLI, HIGH-RESOLUTION, HYPOXIA-INDUCIBLE FACTOR-1-ALPHA, LARGER PROTEINS, NEUROMUSCULAR-JUNCTION, NMR, NMR EXPERIMENTS, protein-protein interaction, RESIDUAL DIPOLAR COUPLINGS, SPECTROSCOPY, TRANSCRIPTION FACTOR, UBIQUITIN},
	isbn = {0022-2836},
	url = {<Go to ISI>://000255374200006},
	author = {Kang, H. S. and Nelson, M. L. and Mackereth, C. D. and Scharpf, M. and Graves, B. J. and McIntosh, L. P.}
}
@article {2140,
	title = {Mechanism and Active Site Residues of GDP-Fucose Synthase},
	journal = {Journal of the American Chemical Society},
	volume = {130},
	number = {51},
	year = {2008},
	note = {ISI Document Delivery No.: 406UOTimes Cited: 3Cited Reference Count: 37Lau, Stephen T. B. Tanner, Martin E.},
	month = {Dec},
	pages = {17593-17602},
	type = {Article},
	abstract = {L-Fucose, 6-deoxy-L-galactose, is a key component of many important glycoconjugates including the blood group antigens and the Lewis(x) ligands. The biosynthesis of GDP-L-fucose begins with the action of a dehydratase that converts GDP-D-mannose into GDP-4-keto-6-deoxy-mannose. The enzyme GDPfucose synthase, GFS, (also known as GDP-4-keto-6-deoxy-D-mannose epimerase/reductase, GMER) then converts GDP-4-keto-6-deoxy-D-mannose into GDP-L-fucose. The GFS reaction involves epimerizations at both C-3 {\textquoteright}{\textquoteright} and C-5 {\textquoteright}{\textquoteright} followed by an NADPH-dependent reduction of the carbonyl at C-4. This manuscript describes studies that elucidate the order of the epimerization steps and the roles of the active site acid/base residues responsible for the epimerizations. An active site mutant, Cys109Ser, produces GDP-6-deoxy-D-altrose as its major product indicating that C-3 {\textquoteright}{\textquoteright} epimerization occurs first and premature reduction of the GDP-4-keto-6-deoxy-D-altrose intermediate becomes competitive with GDP-L-fucose production. The same mutation results in the appearance of a kinetic isotope effect when [3 {\textquoteright}{\textquoteright}-H-2]-GDP-6-deoxy-4-keto-mannose is used as a substrate. This indicates that Cys109 is the base responsible for the deprotonation of the substrate at C-3 {\textquoteright}{\textquoteright}. The Cys109Ser mutant also catalyzes a rapid wash-in of solvent derived deuterium into the C-5 {\textquoteright}{\textquoteright} position of GDP-fucose in the presence of NADP(+). This confirms the order of epimerizations and the role of Cys109. Finally, the inactive His179Gln mutant readily catalyzes the wash-out of deuterium from the C-3 {\textquoteright}{\textquoteright} position of [3 {\textquoteright}{\textquoteright}-H-2]-GDP-6-deoxy-4-keto-mannose. Together these results strongly implicate an ordered sequence of epimerizations (C-3 {\textquoteright}{\textquoteright} followed by C-5 {\textquoteright}{\textquoteright}) and suggest that Cys109 acts as a base and His179 acts as an acid in both epimerization steps.},
	keywords = {6-DEHYDRATASE, ARABIDOPSIS-THALIANA, BIOLOGICAL FUNCTION, CATALYTIC MECHANISM, DTDP-GLUCOSE 4, ESCHERICHIA-COLI, GDP-4-KETO-6-DEOXY-D-MANNOSE EPIMERASE/REDUCTASE, HELICOBACTER-PYLORI, LEUKOCYTE ADHESION, MANNOSE 4, UDP-GALACTOSE 4-EPIMERASE},
	isbn = {0002-7863},
	url = {<Go to ISI>://000263320600076},
	author = {Lau, S. T. B. and Tanner, M. E.}
}
@article {2092,
	title = {Mechanistic Studies on N-Acetylmuramic Acid 6-Phosphate Hydrolase (MurQ): An Etherase Involved in Peptidoglycan Recycling},
	journal = {Biochemistry},
	volume = {47},
	number = {44},
	year = {2008},
	note = {ISI Document Delivery No.: 366TUTimes Cited: 4Cited Reference Count: 37Hadi, Timin Dahl, Ulrike Mayer, Christoph Tanner, Martin E.},
	month = {Nov},
	pages = {11547-11558},
	type = {Article},
	abstract = {Peptidoglycan recycling is a process in which bacteria import cell wall degradation products and incorporate them back into either peptidoglycan biosynthesis or basic metabolic pathways. The enzyme MurQ is an N-acetylmuramic acid 6-phosphate (MurNAc 6-phosphate) hydrolase (or etherase) that hydrolyzes the lactyl side chain from MurNAc 6-phosphate and generates GlcNAc 6-phosphate. This study supports a mechanism involving the syn elimination of lactate to give an alpha,beta-unsaturated aldehyde with (E)-stereochemistry, followed by the syn addition of water to give product. The observation of both a kinetic isotope effect slowing the reaction of [2-H-2]MurNAc 6-phosphate and the incorporation of solvent-derived deuterium into C2 of the product indicates that the C2-H bond is cleaved during catalysis. The observation that the solvent-derived 180 isotope is incorporated into the C3 position of the product, but not the C1 position, provides evidence of the cleavage of the C3-O bond and argues against imine formation. The finding that 3-chloro-3-deoxy-GlcNAc 6-phosphate serves as an alternate substrate is also consistent with an elimination-addition mechanism. Upon extended incubations of MurQ with GlcNAc 6-phosphate, the alpha,beta-unsaturated aldehydic intermediate accumulates in solution, and H-1 NMR analysis indicates it exists as the ring-closed form of the (E)-alkene. A structural model is developed for the Escherichia coli MurQ and is compared to that of the structural homologue glucosamine-6-phosphate synthase. Putative active site acid/base residues are probed by mutagenesis, and Glu83 and Glu114 are found to be crucial for catalysis. The Glu83Ala mutant is essentially inactive as an etherase yet is capable of exchanging the C2 proton of substrate with solvent-derived deuterium. This suggests that Glu83 may function as the acidic residue that protonates the departing lactate.},
	keywords = {CATALYSIS, CELL-WALL, COLI GLUCOSAMINE-6-PHOSPHATE SYNTHASE, DERIVATIVES, ELIMINATION, ENOYL-COA HYDRATASE, ENVIRONMENT, ESCHERICHIA-COLI, INHIBITION, PHOSPHATE},
	isbn = {0006-2960},
	url = {<Go to ISI>://000260507100019},
	author = {Hadi, T. and Dahl, U. and Mayer, C. and Tanner, M. E.}
}
@article {2279,
	title = {Transient oxidation as a mechanistic strategy in enzymatic catalysis},
	journal = {Current Opinion in Chemical Biology},
	volume = {12},
	number = {5},
	year = {2008},
	note = {ISI Document Delivery No.: 375SZTimes Cited: 1Cited Reference Count: 41Tanner, Martin E.},
	month = {Oct},
	pages = {532-538},
	type = {Review},
	abstract = {Enzymes that employ a transient oxidation mechanism catalyze transformations that are overall redox neutral, but involve intermediates that have a higher oxidation state than the substrates or products. An oxidation/reduction sequence may be used directly to promote isomerization reactions or indirectly to permit the formation of stabilized intermediates such as carbanions. This review will focus on three recent examples of nicotinamide-dependent enzymes that have been found to employ transient oxidation during catalysis: ADP-L-glycero-D-manno-heptose 6-epimerase, GDP-mannose 3,5-epimerase, and the 6-phosphoglucosidases from family 4. These enzymes are remarkable in their ability to catalyze either nonstereospecific hydride transfers or multiple chemical steps within a single active site.},
	keywords = {ACTIVE-SITE, ALPHA-GLUCOSIDASE, BACILLUS-SUBTILIS, CRYSTAL-STRUCTURE, D-MANNO-HEPTOSE, D-MANNOHEPTOSE 6-EPIMERASE, DEHYDROQUINATE SYNTHASE, ESCHERICHIA-COLI, THERMOTOGA-MARITIMA, UDP-GALACTOSE 4-EPIMERASE},
	isbn = {1367-5931},
	url = {<Go to ISI>://000261134900010},
	author = {Tanner, M. E.}
}
@article {1213,
	title = {Dismutase activity of ADP-L-glycero-D-manno-heptose 6-epimerase: Evidence for a direct oxidation/reduction mechanism},
	journal = {Biochemistry},
	volume = {44},
	number = {15},
	year = {2005},
	note = {ISI Document Delivery No.: 916ZNTimes Cited: 11Cited Reference Count: 33},
	month = {Apr},
	pages = {5907-5915},
	type = {Article},
	abstract = {The first positive evidence for the utilization of a direct C-6" oxidation/reduction mechanism by ADP-L-glycero-D-manno-heptose 6-epimerase is reported here. The epimerase (HldD or AGME, formerly RfaD) operates in the biosynthetic pathway Of L-glycero-D-manno-heptose, which is a conserved sugar in the core region of lipopolysaccharide (LPS) of Gram-negative bacteria. The stereochemical inversion catalyzed by the epimerase is interesting as it occurs at an "unactivated" stereocenter that lacks an acidic C-H bond, and therefore, a direct deprotonation/reprotonation mechanism cannot be employed. Instead, the epimerase employs a transient oxidation strategy involving a tightly bound NADP(+) cofactor. A recent study ruled out mechanisms involving transient oxidation at C-4 {\textquoteright}{\textquoteright} and C-7 {\textquoteright}{\textquoteright} and supported a mechanism that involves an initial oxidation directly at the C-6 {\textquoteright}{\textquoteright} position to generate a 6"-keto intermediate (Read, J. A., Ahmed, R. A., Morrison, J. P., Coleman, W. G., Jr., Tanner, M. E. (2004) J. Am. Chem. Soc. 126, 8878-8879). A subsequent nonstereospecific reduction of the ketone intermediate can generate either epimer of the ADP-heptose. In this work, an intermediate analogue containing an aldehyde functionality at C-6 {\textquoteright}{\textquoteright}, ADP-beta-D-manno-hexodialdose, is prepared in order to probe the ability of the enzyme to catalyze redox chemistry at this position. It is found that incubation of the aldehyde with a catalytic amount of the epimerase leads to a dismutation process in which one-half of the material is oxidized to ADP-beta-D-mannuronic acid and the other half is reduced to ADP-beta-D-mannose. Transient reduction of the enzyme-bound NADP(+) was monitored by UV spectroscopy and implicates the cofactor{\textquoteright}s involvement during catalysis.},
	keywords = {ACID, ALCOHOL-DEHYDROGENASE, ALDEHYDE DEHYDROGENASE, D-MANNOHEPTOSE 6-EPIMERASE, DROSOPHILA-MELANOGASTER, EPIMERIZATION, ESCHERICHIA-COLI, GLUCOSE DEHYDROGENASE, LIVER, SITE RESIDUES, UDP-GALACTOSE 4-EPIMERASE},
	isbn = {0006-2960},
	url = {<Go to ISI>://000228425600037},
	author = {Morrison, J. P. and Read, J. A. and Coleman, W. G. and Tanner, M. E.}
}
@article {1084,
	title = {Identification and characterization of NeuB3 from Campylobacter jejuni as a pseudaminic acid synthase},
	journal = {Journal of Biological Chemistry},
	volume = {280},
	number = {43},
	year = {2005},
	note = {ISI Document Delivery No.: 976IMTimes Cited: 22Cited Reference Count: 43},
	month = {Oct},
	pages = {35922-35928},
	type = {Article},
	abstract = {Campylobacter jejuni and Campylobacter coli are the main causes of bacterial diarrhea worldwide, and Helicobacter pylori is known to cause duodenal ulcers. In all of these pathogenic organisms, the flagellin proteins are heavily glycosylated with a 2-keto-3-deoxy acid, pseudaminic acid (5,7-diacetamido-3,5,7,9-tetradeoxy-L-glycero-L- manno-nonulosonic acid). The presence of pseudaminic acid is required for the proper development of the flagella and is thereby necessary for motility in, and invasion of, the host. In this study we report the first characterization of NeuB3 from C. jejuni as a pseudaminic acid synthase; the enzyme directly responsible for the biosynthesis of pseudaminic acid. Pseudaminic acid synthase catalyzes the condensation of phosphoenolpyruvate ( PEP) with the hexose, 2,4-diacetamido-2,4,6- trideoxy-L-altrose (6-deoxy-AltdiNAc), to form pseudaminic acid and phosphate. The enzymatic activity was monitored using H-1 and P-31 NMR spectroscopy, and the product was isolated and characterized. Kinetic analysis reveals that pseudaminic acid synthase requires the presence of a divalent metal ion for catalysis and that optimal catalysis occurs at pH 7.0. A coupled enzymatic assay gave the values for k(cat) of 0.65 +/- 0.01 s(-1), KmPEP of 6.5 +/- 0.4 mu M, and K(m)6-deoxy- AltdiNAc of 9.5 +/- 0.7 mu M. A mechanistic study on pseudaminic acid synthase, using[2-O-18] PEP, shows that catalysis proceeds through a C-O bond cleavage mechanism similar to other PEP condensing synthases such as sialic acid synthase.},
	keywords = {BISUBSTRATE INHIBITOR, ESCHERICHIA-COLI, HELICOBACTER-PYLORI, KDO8P SYNTHASE, NEISSERIA-MENINGITIDIS, O-SPECIFIC POLYSACCHARIDE, PNEUMOPHILA SEROGROUP-1 LIPOPOLYSACCHARIDE, PSEUDOMONAS-AERUGINOSA, SIALIC ACIDS, SOMATIC ANTIGENS},
	isbn = {0021-9258},
	url = {<Go to ISI>://000232726900019},
	author = {Chou, W. K. and Dick, S. and Wakarchuk, W. W. and Tanner, M. E.}
}
@article {1127,
	title = {Structural and mechanistic analysis of sialic acid synthase NeuB from Neisseria meningitidis in complex with Mn2+ phosphoenolpyruvate, and N-acetylmannosaminitol},
	journal = {Journal of Biological Chemistry},
	volume = {280},
	number = {5},
	year = {2005},
	note = {ISI Document Delivery No.: 897DJTimes Cited: 19Cited Reference Count: 58},
	month = {Feb},
	pages = {3555-3563},
	type = {Article},
	abstract = {In Neisseria meningitidis and related bacterial pathogens, sialic acids play critical roles in mammalian cell immunity evasion and are synthesized by a conserved enzymatic pathway that includes sialic acid synthase (NeuB, SiaC, or SynC). NeuB catalyzes the condensation of phosphoenolpyruvate (PEP) and N-acetylmannosamine, directly forming N-acetylneuraminic acid (or sialic acid). In this paper we report the development of a coupled assay to monitor NeuB reaction kinetics and an O-18-labeling study that demonstrates the synthase operates via a C-O bond cleavage mechanism. We also report the first structure of a sialic acid synthase, that of NeuB, revealing a unique domain-swapped homodimer architecture consisting of a (beta/alpha)(8) barrel (TIM barrel)type fold at the N-terminal end and a domain with high sequence identity and structural similarity to the ice binding type III antifreeze proteins at the C-terminal end of the enzyme. We have determined the structures of NeuB in the malate-bound form and with bound PEP and the substrate analog N-acetylmannosaminitol to 1.9 and 2.2 Angstrom resolution, respectively. Typical of other TIM barrel proteins, the active site of NeuB is located in a cavity at the C-terminal end of the barrel; however, the positioning of the swapped antifreeze-like domain from the adjacent monomer provides key residues for hydrogen bonding with substrates in the active site of NeuB, a structural feature that leads to distinct modes of substrate binding from other PEP-utilizing enzymes that lack an analogous antifreeze-like domain. Our observation of a direct interaction between a highly ordered manganese and the N-acetylmannosaminitol in the NeuB active site also suggests an essential role for the ion as an electrophilic catalyst that activates the N-acetylmannosamine carbortyl to the addition of PEP.},
	keywords = {3-DEOXY-D-ARABINO-HEPTULOSONATE-7-PHOSPHATE SYNTHASE, 3-DEOXY-D-MANNO-OCTULOSONATE-8-PHOSPHATE SYNTHASE, ACETYLNEURAMINIC ACID, BISUBSTRATE, CAMPYLOBACTER-JEJUNI, CATALYTIC MECHANISM, CELL GLYCOSYLATION, ENZYMATIC SYNTHESIS, ESCHERICHIA-COLI, INHIBITOR, KDO8P SYNTHASE},
	isbn = {0021-9258},
	url = {<Go to ISI>://000226983900053},
	author = {Gunawan, J. and Simard, D. and Gilbert, M. and Lovering, A. L. and Wakarchuk, W. W. and Tanner, M. E. and Strynadka, N. C. J.}
}
@article {847,
	title = {Cyclic enterobacterial common antigen: Potential contaminant of bacterially expressed protein preparations},
	journal = {Journal of Biomolecular Nmr},
	volume = {29},
	number = {2},
	year = {2004},
	note = {ISI Document Delivery No.: 801ZPTimes Cited: 5Cited Reference Count: 10},
	month = {Jun},
	pages = {199-204},
	type = {Article},
	abstract = {We have previously reported the identification of the cyclic enterobacterial common antigen (ECACYC) polysaccharide in E. coli strains commonly used for heterologous protein expression (PJA Erbel et al., J. Bacteriol. 185 ( 2003): 1995). Following this initial report, interactions among several NMR groups established that characteristic N-acetyl signals of ECACYC have been observed in N-15-H-1 HSQC spectra of samples of various bacterially-expressed proteins suggesting that this water-soluble carbohydrate is a common contaminant. We provide NMR spectroscopic tools to recognize ECACYC in protein samples, as well as several methods to remove this contaminant. Early recognition of ECA-based NMR signals will prevent time-consuming analyses of this copurifying carbohydrate.},
	keywords = {enterobacterial common antigen, ESCHERICHIA-COLI, heterologous protein expression, IDENTIFICATION, N-acetylated carbohydrate, NMR-SPECTROSCOPY, protein purification},
	isbn = {0925-2738},
	url = {<Go to ISI>://000220134100007},
	author = {Erbel, P. J. A. and Seidel, R. and Macintosh, S. E. and Gentile, L. N. and Amor, J. C. and Kahn, R. A. and Prestegard, J. H. and McIntosh, L. P. and Gardner, K. H.}
}
@article {998,
	title = {Identification and quantification of arsC genes in environmental samples by using real-time PCR},
	journal = {Journal of Microbiological Methods},
	volume = {58},
	number = {3},
	year = {2004},
	note = {ISI Document Delivery No.: 847SSTimes Cited: 24Cited Reference Count: 34},
	month = {Sep},
	pages = {335-349},
	type = {Article},
	abstract = {The arsC gene is responsible for the first step in arsenate biotransformation encoding the enzyme arsenate reductase. The quantitative real-time PCR method was developed to quantify the abundance of the arsC genes in environmental samples contaminated with arsenic. Two sets of primers that showed high specificity for the target arsC gene were designed based on consensus sequences from 13 bacterial species. The arsC gene was used as an external standard instead of total DNA in the calibration curve for real-time PCR, which was linear over six orders of magnitude and the detection limit was estimated to be about three copies of the gene. Soil samples from arsenic contaminated sites were screened for arsC genes by using PCR and showed the presence of this gene. The copy numbers of the gene ranging from 0.88 x 10(4) to 1.56 x 10(5) per ng total DNA were found in eight arsenic contaminated samples. Soil samples from a bioreactor containing pulp mill biomass and high concentration of arsenate showed a tenfold higher count of arsC gene copies than soil samples collected underground from an arsenic-rich gold mine. (C) 2004 Elsevier B.V. All rights reserved.},
	keywords = {arsC gene, arsenate reduction, ASSAY, BACTERIA, DNA, ESCHERICHIA-COLI, group-specific primers, QUANTITATION, real-time PCR, REDUCTION, resistance, SOIL, SYBR (R) Green 1},
	isbn = {0167-7012},
	url = {<Go to ISI>://000223415800006},
	author = {Sun, Y. M. and Polishchuk, E. A. and Radoja, U. and Cullen, W. R.}
}
@article {966,
	title = {The mechanism of the reaction catalyzed by ADP-beta-L-glycero-D-manno-heptose 6-epimerase},
	journal = {Journal of the American Chemical Society},
	volume = {126},
	number = {29},
	year = {2004},
	note = {ISI Document Delivery No.: 840JTTimes Cited: 14Cited Reference Count: 24},
	month = {Jul},
	pages = {8878-8879},
	type = {Article},
	keywords = {4, 6-DEHYDRATASE, BACTERIA, D-MANNOHEPTOSE 6-EPIMERASE, EPIMERIZATION, ESCHERICHIA-COLI, GLUCOSE, INSIGHTS, NUCLEOTIDE-MODIFYING ENZYMES, OUTER-MEMBRANE, UDP-GALACTOSE 4-EPIMERASE},
	isbn = {0002-7863},
	url = {<Go to ISI>://000222855300009},
	author = {Read, J. A. and Ahmed, R. A. and Morrison, J. P. and Coleman, W. G. and Tanner, M. E.}
}
@article {976,
	title = {Structural characterization of the RNase E S1 domain and identification of its oligonucleotide-binding and dimerization interfaces},
	journal = {Journal of Molecular Biology},
	volume = {341},
	number = {1},
	year = {2004},
	note = {ISI Document Delivery No.: 841JCTimes Cited: 25Cited Reference Count: 65},
	month = {Jul},
	pages = {37-54},
	type = {Article},
	abstract = {S1 domains occur in four of the major enzymes of mRNA decay in Escherichia coli: RNase E, PNPase, RNase II, and RNase G. Here, we report the structure of the S1 domain of RNase E, determined by both X-ray crystallography and NMR spectroscopy. The RNase E S1 domain adopts an OB-fold, very similar to that found with PNPase and the major cold shock proteins, in which flexible loops are appended to a well-ordered five-stranded beta-barrel core. Within the crystal lattice, the protein forms a dimer stabilized primarily by intermolecular hydrophobic packing. Consistent with this observation, light-scattering, chemical crosslinking, and NMR spectroscopic measurements confirm that the isolated RNase E S1 domain undergoes a specific monomer-dimer equilibrium in solution with a K-D value in the millimolar range. The substitution of glycine 66 with serine dramatically destabilizes the folded structure of this domain, thereby providing an explanation for the temperature-sensitive phenotype associated with this mutation in full-length RNase E. Based on amide chemical shift perturbation mapping, the binding surface for a single-stranded DNA dodecamer (K-D = 160(+/-40) muM) was identified as a groove of positive electrostatic potential containing several exposed aromatic side-chains. This surface, which corresponds to the conserved ligand-binding cleft found in numerous OB-fold proteins, lies distal to the dimerization interface, such that two independent oligonucleotide-binding sites can exist in the dimeric form of the RNase E S1 domain. Based on these data, we propose that the S1 domain serves a dual role of dimerization to aid in the formation of the tetrameric quaternary structure of RNase E as described by Callaghan et al. in 2003 and of substrate binding to facilitate RNA hydrolysis by the adjacent catalytic domains within this multimeric enzyme. (C) 2004 Elsevier Ltd. All rights reserved.},
	keywords = {BACILLUS-SUBTILIS, C-13-LABELED PROTEINS, CELLULOMONAS-FIMI, CENC, CHEMICAL-SHIFT, COLD-SHOCK PROTEIN, ESCHERICHIA-COLI, MACROMOLECULAR STRUCTURES, MESSENGER-RNA, OB-fold, protein structure, RNA binding, RNase E, ROTATIONAL DIFFUSION, S1 domain, SELECTIVE H-1-N-15 CORRELATIONS},
	isbn = {0022-2836},
	url = {<Go to ISI>://000222925100005},
	author = {Schubert, M. and Edge, R. E. and Lario, P. and Cook, M. A. and Strynadka, N. C. J. and Mackie, G. A. and McIntosh, L. P.}
}
@article {389,
	title = {The solution structure and interactions of CheW from Thermotoga maritima},
	journal = {Nature Structural Biology},
	volume = {9},
	number = {2},
	year = {2002},
	note = {ISI Document Delivery No.: 516PHTimes Cited: 35Cited Reference Count: 34},
	month = {Feb},
	pages = {121-125},
	type = {Article},
	abstract = {Using protein from the hyperthermophile Thermotoga maritima, we have determined the solution structure of CheW, an essential component in the formation of the bacterial chemotaxis signaling complex. The overall fold is similar to the regulatory domain of the chemotaxis kinase CheA. In addition, interactions of CheW with CheA were monitored by nuclear magnetic resonance (NMR) techniques. The chemical shift perturbation data show the probable contacts that CheW makes with CheA. In combination with previous genetic data, the structure also suggests a possible binding site for the chemotaxis receptor. These results provide a structural basis for a model in which CheW acts as a molecular bridge between CheA and the cytoplasmic tails of the receptor.},
	keywords = {BACTERIAL CHEMOTAXIS, BINDING DOMAIN, C-13-LABELED PROTEINS, ESCHERICHIA-COLI, HISTIDINE KINASE, KINASE CHEA, NMR EXPERIMENTS, RESONANCE ASSIGNMENTS, SECONDARY STRUCTURE, SIGNAL-TRANSDUCTION},
	isbn = {1072-8368},
	url = {<Go to ISI>://000173562000015},
	author = {Griswold, I. J. and Zhou, H. J. and Matison, M. and Swanson, R. V. and McIntosh, L. P. and Simon, M. I. and Dahlquist, F. W.}
}
@article {520,
	title = {Understanding nature{\textquoteright}s strategies for enzyme-catalyzed racemization and epimerization},
	journal = {Accounts of Chemical Research},
	volume = {35},
	number = {4},
	year = {2002},
	note = {ISI Document Delivery No.: 544TBTimes Cited: 65Cited Reference Count: 36},
	month = {Apr},
	pages = {237-246},
	type = {Review},
	abstract = {Epimerases and racemases are enzymes that catalyze the inversion of stereochemistry in biological molecules. In this article, three distinct examples are used to illustrate the wide range of chemical strategies employed during catalysis, and the diverse set of ancestors from which these enzymes have evolved. Glutamate racemase is an example of an enzyme that operates at an "activated" stereocenter (bearing a relatively acidic proton) and employs a nonstereospecific deprotonation/reprotonation mechanism. UDP-N-Acetylglucosamine 2-epimerase acts at an "unactivated" stereocenter and uses a mechanism involving a nonstereospecific elimination/addition of UDP. L-Ribulose phosphate 4-epimerase also acts at an unactivated stereocenter and uses a nonstereospecific retroaldol/aldol mechanism.},
	keywords = {ALDOLASE, CLASS-II, ESCHERICHIA-COLI, GLUTAMATE RACEMASE, IDENTIFICATION, L-FUCULOSE-1-PHOSPHATE, L-RIBULOSE-5-PHOSPHATE 4-EPIMERASE, MECHANISM, N-ACETYLGLUCOSAMINE 2-EPIMERASE, PHOSPHATE, RESIDUES},
	isbn = {0001-4842},
	url = {<Go to ISI>://000175175800005},
	author = {Tanner, M. E.}
}
@article {5082,
	title = {Active site residues of glutamate racemase},
	journal = {Biochemistry},
	volume = {40},
	number = {21},
	year = {2001},
	note = {ISI Document Delivery No.: 436GCTimes Cited: 44Cited Reference Count: 38},
	month = {May},
	pages = {6199-6204},
	type = {Article},
	abstract = {Glutamate racemase, MurI, catalyzes the interconversion of glutamate enantiomers in a cofactor-independent fashion and provides bacteria with a source of D-Glu for use in peptidoglycan biosynthesis. The enzyme uses a "two-base" mechanism involving a deprotonation of the substrate at the ct-position to form an anionic intermediate, followed by a reprotonation in the opposite stereochemical sense. In the Lactobacillus fermenti enzyme, Cys73 is responsible for the deprotonation of D-glutamate, and Cys184 is responsible for the deprotonation of L-glutamate; however, very little is known about the roles of other active site residues. This work describes the preparation of four mutants in which strictly conserved residues containing ionizable side chains were modified (D10N, D36N, E152Q, and H186N). During the course of this research, the structural analysis of a crystallized glutamate racemase indicated that three of these residues (D10, E152, and H186) are in the active site of the enzyme [Hwang, K. Y., Cho, C.-S., Kim, S. S., Sung, H.-C., Yu, Y. G., and Cho, Y. (1999) Nat. Struct. Biol. 6, 422-426]. Two of the mutants, D10N and H186N, displayed a marked decrease in the values of k(cat), but not K-M, and are therefore implicated as important catalytic residues. Further analysis of the primary kinetic isotope effects observed with a-deuterated substrates showed that a significant asymmetry was introduced into the free energy profile by these two mutations. This is interpreted as evidence that the mutated residues normally assist the catalytic thiols in acting as bases (D10 with C73 and H186 with C184). An alternate possibility is that the residues may serve to stabilize the carbanionic intermediate in the racemization reaction.},
	keywords = {AMINO-ACID RACEMASE, AQUIFEX PYROPHILUS, CARBON ACIDS, ENZYME-CATALYZED REACTIONS, ESCHERICHIA-COLI, INFLUENZAE DIAMINOPIMELATE EPIMERASE, IRREVERSIBLE INHIBITOR, MANDELATE RACEMASE, PROLINE, PROTON ABSTRACTION, RACEMASE},
	isbn = {0006-2960},
	url = {<Go to ISI>://000168927300002},
	author = {Glavas, S. and Tanner, M. E.}
}
@article {5031,
	title = {Artificial nucleases},
	journal = {Chembiochem},
	volume = {2},
	number = {10},
	year = {2001},
	note = {ISI Document Delivery No.: 479NGTimes Cited: 54Cited Reference Count: 25},
	month = {Oct},
	pages = {735-740},
	type = {Article},
	abstract = {The oxidation of DNA and RNA provides a facile approach for investigating the interaction of nucleic acids wit proteins and oligonucleotides In this article, we have outlined our understanding of the mechanism of DNA scission by 1,10-phenanthroline-copper(I) in the presence of hydrogen peroxide. We also discuss results obtained by using 1,10-phenanthroline - oligonucleotide conjugates in probing the size of the transcriptionally active open complex. Finally, we outline an effective method for converting DNA-binding proteins into site-specific modification agents by using 1,10-phenanthroline-copper(I).},
	keywords = {1, 10-PHENANTHROLINE-COPPER ION, chemical, COLI RNA-POLYMERASE, COMPLEX, copper, DNA, DNA cleavage, DNA recognition, ESCHERICHIA-COLI, NUCLEASE, nucleic acids, OLIGONUCLEOTIDES, PROTEIN, SITE-SPECIFIC NUCLEASE, TRANSCRIPTION INITIATION},
	isbn = {1439-4227},
	url = {<Go to ISI>://000171410000003},
	author = {Chen, C. H. B. and Milne, L. and Landgraf, R. and Perrin,David M. and Sigman, D. S.}
}
@article {5183,
	title = {Catalysis and binding in L-ribulose-5-phosphate 4-epimerase: A comparison with L-fuculose-1-phosphate aldolase},
	journal = {Biochemistry},
	volume = {40},
	number = {49},
	year = {2001},
	note = {ISI Document Delivery No.: 500CJTimes Cited: 15Cited Reference Count: 15},
	month = {Dec},
	pages = {14772-14780},
	type = {Article},
	abstract = {L-Ribulose-5-phosphate (L-Ru5P) 4-epimerase and L-fuculose-1-phosphate (L-Fuc1P) aldolase are evolutionarily related enzymes that display 26\% sequence identity and a very high degree of structural similarity. They both employ a divalent cation in the formation and stabilization of an enolate during catalysis, and both are able to deprotonate the C-4 hydroxyl group of a phosphoketose substrate. Despite these many similarities, subtle distinctions must be present which allow the enzymes to catalyze two seemingly different reactions and to accommodate substrates differing greatly in the position of the phosphate (C-5 vs C-1). Asp76 of the epimerase corresponds to the key catalytic acid/base residue Glu73 of the aldolase. The D76N mutant of the epimerase retained considerable activity, indicating it is not a key catalytic residue in this enzyme. In addition, the D76E mutant did not show enhanced levels of background aldolase activity. Mutations of residues in the putative phosphate-binding pocket of the epimerase (N28A and K42M) showed dramatically higher values of K-M for L-Ru5P. This indicates that both enzymes utilize the same phosphate recognition pocket, and since the phosphates are positioned at opposite ends of the respective substrates, the two enzymes must bind their substrates in a reversed or "flipped" orientation. The epimerase mutant D120N displays a 3000-fold decrease in the value of k(cat), suggesting that Asp 120{\textquoteright} provides a key catalytic acid/base residue in this enzyme. Analysis of the D120N mutant by X-ray crystallography shows that its structure is indistinguishable from that of the wild-type enzyme and that the decrease in activity was not simply due to a structural perturbation of the active site. Previous work [Lee, L.V., Poyner, R.R., Vu, M.V., and Cleland, W.W. (2000) Biochemistry 39, 4821-4830] has indicated that Tyr229{\textquoteright} likely provides the other catalytic acid/base residue. Both of these residues are supplied by an adjacent subunit. Modeling Of L-Ru5P into the active site of the epimerase structure suggests that Tyr229{\textquoteright} is responsible for deprotonating L-Ru5P and Asp 120{\textquoteright} is responsible for deprotonating its epimer, D-Xu5P.},
	keywords = {CLASS-II, CLEAVAGE, ESCHERICHIA-COLI, MECHANISM, MUTAGENESIS, PHOSPHATE},
	isbn = {0006-2960},
	url = {<Go to ISI>://000172608100006},
	author = {Samuel, J. and Luo, Y. and Morgan, P. M. and Strynadka, N. C. J. and Tanner, M. E.}
}
@article {5138,
	title = {The structure of L-ribulose-5-phosphate 4-epimerase: An aldolase-like platform for epimerization},
	journal = {Biochemistry},
	volume = {40},
	number = {49},
	year = {2001},
	note = {ISI Document Delivery No.: 500CJTimes Cited: 18Cited Reference Count: 45},
	month = {Dec},
	pages = {14763-14771},
	type = {Article},
	abstract = {The structure of L-ribulose-5 -phosphate 4-epimerase from E. coli has been solved to 2.4 Angstrom resolution using X-ray diffraction data. The structure is homo-tetrameric and displays C-4 symmetry. Each subunit has a single domain comprised of a central beta -sheet flanked on either side by layers of alpha -helices. The active site is identified by the position of the catalytic zinc residue and is located at the interface between two adjacent subunits. A remarkable feature of the structure is that it shows a very close resemblance to that of L-fuculose-1-phosphate aldolase. This is consistent with the notion that both enzymes belong to a superfamily of epimerases/aldolases that catalyze carbon-carbon bond cleavage reactions via a metal-stabilized enolate intermediate. Detailed inspection of the epimerase structure, however, indicates that despite the close overall structural similarity to class II aldolases, the enzyme has evolved distinct active site features that promote its particular chemistry.},
	keywords = {CHEMISTRY, CLASS-II, CLEAVAGE, ENZYME, ESCHERICHIA-COLI, EVOLUTION, GALACTOSE, L-FUCULOSE-1-PHOSPHATE ALDOLASE, MECHANISM, SEQUENCE, SUPERFAMILIES},
	isbn = {0006-2960},
	url = {<Go to ISI>://000172608100005},
	author = {Luo, Y. and Samuel, J. and Mosimann, S. C. and Lee, J. E. and Tanner, M. E. and Strynadka, N. C. J.}
}
@article {4856,
	title = {Binding site analysis of cellulose binding domain CBDN1 from endoglucanse C of Cellulomonas fimi by site-directed mutagenesis},
	journal = {Biochemistry},
	volume = {39},
	number = {30},
	year = {2000},
	note = {ISI Document Delivery No.: 339RJTimes Cited: 17Cited Reference Count: 59},
	month = {Aug},
	pages = {8844-8852},
	type = {Article},
	abstract = {Endoglucanase C (CenC), a beta 1,4 glucanase from the soil bacterium Cellulomonas fimi, binds to amorphous cellulose via two homologous cellulose binding domains, termed CBDN1 and CBDN2. in this work, the contributions of 10 amino acids within the binding cleft of CBDN1 were evaluated by single site-directed mutations to alanine residues. Each isolated domain containing a single mutation was analyzed for binding to an insoluble amorphous preparation of cellulose, phosphoric acid swollen Avicel (PASA), and to a soluble glucopyranoside polymer, barley beta-glucan. The effect of any given mutation on CBD binding was similar for both substrates, suggesting that the mechanism of binding to soluble and insoluble substrates is the same. Tyrosines 19 and 85 were essential for tight binding by CBDN1 as their replacement by alanine results in affinity decrements of approximately 100-fold on PASA, barley beta-glucan, and soluble cellooligosaccharides. The tertiary structures of unbound Y19A and Y85A were assessed by heteronuclear single quantum coherence (HSQC) spectroscopy. These studies indicated that the structures of both mutants were perturbed but that all perturbations are very near to the site of mutation.},
	keywords = {4-GLUCANASE CENC, BETA-1, ESCHERICHIA-COLI, LIGAND-BINDING, LIMITED PROTEOLYSIS, MECHANISM, N-ACETYLGLUCOSAMINE, NUCLEAR-MAGNETIC-RESONANCE, REESEI CELLOBIOHYDROLASE-I, TRICHODERMA-REESEI, TRYPTOPHAN RESIDUES},
	isbn = {0006-2960},
	url = {<Go to ISI>://000088491500018},
	author = {Kormos, J. and Johnson, P. E. and Brun, E. and Tomme, P. and McIntosh, L. P. and Haynes, C. A. and Kilburn, D. G.}
}
@article {4751,
	title = {The first structure of UDP-glucose dehydrogenase reveals the catalytic residues necessary for the two-fold oxidation},
	journal = {Biochemistry},
	volume = {39},
	number = {23},
	year = {2000},
	note = {ISI Document Delivery No.: 324PRTimes Cited: 62Cited Reference Count: 49},
	month = {Jun},
	pages = {7012-7023},
	type = {Article},
	abstract = {Bacterial UDP-glucose dehydrogenase (UDPGlcDH) is essential for formation of the antiphagocytic capsule that protects many virulent bacteria such as Streptococcus pyrogenes and Streptococcus pneumoniae type 3 from the host{\textquoteright}s immune system. We have determined the X-ray structures of both native and Cys260Ser UDPGlcDH from S. pyogenes (74\% similarity to S. pneumoniae) in ternary complexes with UDP-xylose/NAD(+) and UDP-glucuronic acid/NAD(H), respectively. The 402 residue homodimeric UDPGlcDH is composed of an N-terminal NAD(+) dinucleotide binding domain and a C-terminal UDP-sugar binding domain connected by a long (48 Angstrom) central alpha-helix. The first 290 residues of UDPGlcDH share structural homology with 6-phosphogluconate dehydrogenase, including conservation of an active site lysine and asparagine that are implicated in the enzyme mechanism. Also proposed to participate in the catalytic mechanism are a threonine and a glutamate that hydrogen bond to a conserved active site water molecule suitably positioned for general acid/base catalysis.},
	keywords = {alanine, ALIGNMENT, CRYSTAL-STRUCTURE, ESCHERICHIA-COLI, GROUP-A STREPTOCOCCI, INSIGHTS, MECHANISM, MOLECULAR CHARACTERIZATION, REDUCTASE, SUBSTRATE-BINDING},
	isbn = {0006-2960},
	url = {<Go to ISI>://000087631000031},
	author = {Campbell, R. E. and Mosimann, S. C. and van de Rijn, I. and Tanner, M. E. and Strynadka, N. C. J.}
}
@article {4557,
	title = {Catalytic acid/base residues of glutamate racemase},
	journal = {Biochemistry},
	volume = {38},
	number = {13},
	year = {1999},
	note = {ISI Document Delivery No.: 182QZTimes Cited: 43Cited Reference Count: 37},
	month = {Mar},
	pages = {4106-4113},
	type = {Article},
	abstract = {Glutamate racemase is a cofactor-independent enzyme that employs two active-site cysteine residues as acid/base catalysts during the interconversion of glutamate enantiomers, In a given reaction direction, a thiolate from one of the cysteines abstracts the alpha-proton, and the other cysteine thiol delivers a proton to the opposite face of the resulting carbanionic intermediate. This paper reports that the C73S and C184S mutants are still capable of racemizing glutamate with specificity constants about 10(3)-fold lower than those of the wild-type enzyme, A "one-base requiring" reaction, the elimination of water from N-hydroxyglutamate, has been used to deduce which thiol acts as the base for a given enantiomer. With D-N-hydroxyglutamate the C73S mutant is a much poorer catalyst than wild-type enzyme, whereas the C184S mutant is a somewhat better catalyst. This trend was reversed with L-N-hydroxyglutamate, suggesting that Cys73 is responsible for the deprotonation of D-glutamate and Cys184 is responsible for the deprotonation of L-glutamate. In addition, with C73S the V-max/K-M isotope effect on D-glutamate racemization was greater than that seen with wild-type enzyme, whereas the isotope effect with L-glutamate had decreased. The results were reversed with the C184S mutant. This is interpreted as being due to an asymmetry in the free energy profiles that is induced upon mutation, with the deprotonation step involving a serine becoming the more cleanly rate-determining of the two. These results support the above assignment and the notion that a carbanionic intermediate is formed during catalysis.},
	keywords = {BACILLUS-STEAROTHERMOPHILUS, DIAMINOPIMELATE EPIMERASE, ENERGETICS, ESCHERICHIA-COLI, INHIBITOR, IRREVERSIBLE, L-ALANINE, MANDELATE RACEMASE, MECHANISM, PROLINE RACEMASE, PURIFICATION},
	isbn = {0006-2960},
	url = {<Go to ISI>://000079510800031},
	author = {Glavas, S. and Tanner, M. E.}
}
@article {4694,
	title = {An iron-based molecular redox switch as a model for iron release from enterobactin via the salicylate binding mode},
	journal = {Inorganic Chemistry},
	volume = {38},
	number = {22},
	year = {1999},
	note = {ISI Document Delivery No.: 255LLTimes Cited: 18Cited Reference Count: 51},
	month = {Nov},
	pages = {5007-5017},
	type = {Article},
	abstract = {The iron release mechanism from protonated ferric enterobactin [Fe-III(enterobactinH(3))] via the salicylate binding mode was probed. For this purpose, a tripodal dodecadentate Ligand incorporating three salicylamide (OO) and three bipyridine (NN) binding sites was synthesized as well as iron complexes thereof. It was shown that a ferric ion coordinates selectively to the hard salicylamides and a ferrous ion binds to the softer bipyridines. Upon reduction or oxidation, the iron translocates reversibly and intramolecularly from one site to the other, thus displaying switchlike properties. Both states were characterized by cyclic voltammetry and visible and Mossbauer spectroscopy. The Mossbauer spectrum for the ferric complex is fully consistent with that obtained by Pecoraro et al. upon lowering the pH of [Fe-III(enterobactin)](3-) solutions (Pecoraro, V. L., et al. J. Am. Chern. Sec. 1983, 105, 4617), thus supporting the alternative iron release mechanism from enterobactin via the salicylate binding mode.},
	keywords = {COORDINATION CHEMISTRY, ESCHERICHIA-COLI, FERRIC ENTEROBACTIN, IRON(III) COORDINATION, LIGAND, METAL-COMPLEXES, SEQUESTERING AGENTS, SYNTHETIC ANALOGS, TRANSLOCATION, TRANSPORT COMPOUNDS},
	isbn = {0020-1669},
	url = {<Go to ISI>://000083670200015},
	author = {Ward, T. R. and Lutz, A. and Parel, S. P. and Ensling, J. and Gutlich, P. and Buglyo, P. and Orvig, Chris}
}
@article {4600,
	title = {Methylarsenicals and arsinothiols are potent inhibitors of mouse liver thioredoxin reductase},
	journal = {Chemical Research in Toxicology},
	volume = {12},
	number = {10},
	year = {1999},
	note = {ISI Document Delivery No.: 248DFTimes Cited: 114Cited Reference Count: 64},
	month = {Oct},
	pages = {924-930},
	type = {Article},
	abstract = {Thioredoxin reductase (TR, EC 1.6.4.5) was purified 5800-fold from the livers of adult male B6C3F1 mice. The estimated molecular mass of the purified protein was about 57 kDa, The activity of the purified enzyme was monitored by the NADPH-dependent reduction of 5,5{\textquoteright}-dithiobis(2-nitrobenzoic acid) (DTNB); this activity was fully inhibited by 1 mu M aurothioglucose. Arsenicals and arsinothiols, complexes of As-III-containing compounds with L-cysteine or glutathione, were tested as inhibitors of the DTNB reductase activity of the purified enzyme. Pentavalent arsenicals were much less potent inhibitors than trivalent arsenicals. Among all the arsenicals, CH3AsIII was the most potent inhibitor of TR. CH3AsIII was found to be a competitive inhibitor of the reduction of DTNB (K-i similar to 100 nM) and a noncompetitive inhibitor of the oxidation of NADPH. The inhibition of TR by CH3AsIII was time-dependent and could not be reversed by the addition of a dithiol-containing molecule, 2,3-dimercaptosuccinic acid, to the reaction mixture. The inhibition of TR by CH3AsIII required the simultaneous presence of NADPH in the reaction mixture. However, unlike other pyridine nucleotide disulfide oxidoreductases, there was no evidence that mouse liver TR was inactivated by exposure to NADPH. Treatment with CH3AsIII did not increase the NADPH oxidase activity of the purified enzyme. Thus, CH3AsIII, a putative intermediate in the pathway for the biomethylation of As, is a potent and irreversible inhibitor of an enzyme involved in the response of the cell to oxidative stress.},
	keywords = {ARSENATE REDUCTASE, CANCER-CELLS, ENDOTHELIAL-CELLS, ESCHERICHIA-COLI, GLUTATHIONE-REDUCTASE, KAPPA-B ACTIVATION, LIPOAMIDE DEHYDROGENASE, MAMMALIAN THIOREDOXIN, MULTI-ENZYME COMPLEX, RABBIT ERYTHROCYTES},
	isbn = {0893-228X},
	url = {<Go to ISI>://000083259500008},
	author = {Lin, S. and Cullen, W. R. and Thomas, D. J.}
}
@article {4298,
	title = {Epimerization via carbon-carbon bond cleavage. L-ribulose-5-phosphate 4-epimerase as a masked class II aldolase},
	journal = {Biochemistry},
	volume = {37},
	number = {16},
	year = {1998},
	note = {ISI Document Delivery No.: ZM208Times Cited: 32Cited Reference Count: 35},
	month = {Apr},
	pages = {5746-5754},
	type = {Article},
	abstract = {Studies indicating that the E. coli L-ribulose-5-phosphate 4-epimerase employs an "aldolase-like" mechanism are reported. This NAD(+)-independent enzyme epimerizes a steseocenter that does not bear an acidic proton and therefore it cannot utilize a simple deprotonation-reprotonation mechanism. Sequence similarities between the epimerase and the class II L-fuculose-1-phosphate aldolase suggest that the two may be evolutionarily related and that the epimerization may occur via carbon-carbon bond cleavage and re-formation. Conserved residues thought to provide the metal ion ligands of the epimerase have been modified using site-directed mutagenesis. The resulting mutants show low k(cat) values in addition to a reduced affinity for Zn2+. These observations serve to establish that there is a structural link between between the active site geometry of the epimerase and the aldolase. In addition, the H97N mutant was found to catalyze the condensation of dihydroxyacetone and glycolaldehyde phosphate to produce a mixture of L-ribulose-5-phosphate and D-xylulose-5-phosphate. This observation of aldolase activity establishes that the epimerase active site is capable of promoting carbon-carbon bond cleavage. Furthermore, glycolaldehyde phosphate was shown to be a competitive inhibitor of the mutant enzyme (K-t = 0.37 mM) but not of the wild-type enzyme. The mutation apparently causes the epimerase to become "leaky" and enables it to bind/generate the normal reaction intermediates from the unbound aldol cleavage products.},
	keywords = {ENZYMES, ESCHERICHIA-COLI, L-FUCULOSE-1-PHOSPHATE ALDOLASE, MECHANISM, MUTAGENESIS, ORGANIC-SYNTHESIS, PCR, PURIFICATION, SEQUENCE, SITE},
	isbn = {0006-2960},
	url = {<Go to ISI>://000073515500048},
	author = {Johnson, A. E. and Tanner, M. E.}
}
@article {4448,
	title = {A phosphinate inhibitor of the meso-diaminopimelic acid-adding enzyme (MurE) of peptidoglycan biosynthesis},
	journal = {Journal of Organic Chemistry},
	volume = {63},
	number = {26},
	year = {1998},
	note = {ISI Document Delivery No.: 153LPTimes Cited: 37Cited Reference Count: 50},
	month = {Dec},
	pages = {10081-10085},
	type = {Article},
	keywords = {AMINO-ACIDS, COLI GLUTAMINE-SYNTHETASE, D-ALANINE LIGASE, ESCHERICHIA-COLI, GLUTATHIONE SYNTHETASE, INACTIVATION, KINETIC MECHANISM, MECHANISM-BASED, N-ACETYLMURAMATE, RAPID-QUENCH, VANCOMYCIN RESISTANCE},
	isbn = {0022-3263},
	url = {<Go to ISI>://000077834800087},
	author = {Zeng, B. Q. and Kwong, K. and Pompliano, D. L. and Reddy, S. and Tanner, M. E.}
}
@article {4236,
	title = {Stability and oligosaccharide binding of the N1 cellulose-binding domain of Cellulomonas fimi endoglucanase CenC},
	journal = {Biochemistry},
	volume = {37},
	number = {10},
	year = {1998},
	note = {ISI Document Delivery No.: ZC900Times Cited: 16Cited Reference Count: 75},
	month = {Mar},
	pages = {3529-3537},
	type = {Article},
	abstract = {Differential scanning calorimetry has been used to study the thermal stability and oligosaccharide-binding thermodynamics of the N-terminal cellulose-binding domain of Cellulomonas fimi beta-1,4-glucanase CenC (CBDN1) CBDN1 has a relatively low maximum stability (Delta G(max) = 33 kJ/mol = 216 J/residue at 1 degrees C and pH 6.1) compared to other small single-domain globular proteins. The unfolding is fully reversible between pH 5.5 and 9 and in accordance with the two-state equilibrium model between pH 5.5 and 11. When the single disulfide bond in CBDN1 is reduced, the protein remains unfolded at all conditions, as judged by NMR spectroscopy. This indicates that the intramolecular cross-link makes a major contribution to the stability of CBDN1. The measured heat capacity change of unfolding (Delta C-p = 7.5 kJ mol(-1) K-1) agrees well with that calculated from the predicted changes in the solvent accessible nonpolar and polar surface areas upon unfolding. Extrapolation of the specific enthalpy and entropy of unfolding to their respective convergence temperature indicates that per residue unfolding energies for CBDN1, an isolated domain, are in accordance with those found by Privalov (1) for many single-domain globular proteins. DSC thermograms of the unfolding of CBDN1 in the presence of various concentrations of cellopentaose were fit to a thermodynamic model describing the linkage between protein-ligand binding and protein unfolding. A global two-dimensional minimization routine is used to regress the binding enthalpy, binding constant, and unfolding thermodynamics for the CBDN1-cellopentaose system. Extrapolated binding constants are in quantitative agreement with those determined by isothermal titration calorimetry at 35 degrees C.},
	keywords = {ASPERGILLUS-NIGER, BRIDGES, differential scanning calorimetry, Disulfide, ESCHERICHIA-COLI, GLOBULAR-PROTEINS, INHIBITOR BINDING, LIGAND-BINDING, PROTEIN-FOLDING THERMODYNAMICS, THERMAL-DENATURATION, TITRATION CALORIMETRY},
	isbn = {0006-2960},
	url = {<Go to ISI>://000072630300034},
	author = {Creagh, A. L. and Koska, J. and Johnson, P. E. and Tomme, P. and Joshi, M. D. and McIntosh, L. P. and Kilburn, D. G. and Haynes, C. A.}
}
@article {4074,
	title = {Eliminations in the reactions catalyzed by UDP-N-acetylglucosamine 2-epimerase},
	journal = {Journal of the American Chemical Society},
	volume = {119},
	number = {43},
	year = {1997},
	note = {ISI Document Delivery No.: YD815Times Cited: 33Cited Reference Count: 65},
	month = {Oct},
	pages = {10269-10277},
	type = {Article},
	abstract = {Mechanistic studies have been carried out on the bacterial enzyme UDP-N-acetylglucosamine 2-epimerase, which catalyzes the interconversion of UDP-N-acetylglucosamine (UDP-GlcNAc) and UDP-N-acetylmannosamine (UDP-ManNAc). This enzyme is interesting because it epimerizes a stereocenter that does not bear an acidic proton, and therefore it cannot utilize a simple deprotonation/reprotonation mechanism. A coupled enzyme assay employing UDP-ManNAc dehydrogenase has been developed. The epimerization in D2O is found to be accompanied by the incorporation of deuterium into the C-2 {\textquoteright}{\textquoteright} position of both epimers, supporting a mechanism that ultimately involves a proton transfer at this position. The epimerization of [2 {\textquoteright}{\textquoteright}-H-2]UDP-GlcNAc is slowed by a primary kinetic isotope effect indicating that C-H bond cleavage is occurring during a rate-determining step of the reaction. A positional isotope exchange (PM) experiment shows that an O-18 label in the sugar-UDP bridging position will scramble into nonbridging diphosphate positions during enzymatic epimerization. These observations are consistent with a mechanism that proceeds via cleavage of the anomeric C-O bond, with 2-acetamidoglucal and UDP as enzyme-bound intermediates. Additional evidence for this mechanism is found in the unusual observation that during extended incubations, the intermediates are gradually released from the enzyme and accumulate in solution. These intermediates are formed by an anti elimination of UDP from UDP-GlcNAc and a syn elimination of UDP from UDP-ManNAc. It is likely that El-like eliminations via oxocarbenium intermediates are involved in the reaction. Further experiments show that 3 {\textquoteright}{\textquoteright}-deoxy-UDP-GlcNAc is not a substrate for the enzyme and that the enzyme does not contain a tightly bound NAD(+) cofactor.},
	keywords = {BACILLUS-SUBTILIS, D-GLUCOSAMINE 2-EPIMERASE, enterobacterial common antigen, ESCHERICHIA-COLI, FATTY-ACID OXIDATION, GALACTOSE 4-EPIMERASE, POSITIONAL ISOTOPE EXCHANGE, RAT-LIVER, STAPHYLOCOCCUS-AUREUS-H, TEICHOIC-ACIDS, W23},
	isbn = {0002-7863},
	url = {<Go to ISI>://A1997YD81500003},
	author = {Morgan, P. M. and Sala, R. F. and Tanner, M. E.}
}
@article {3956,
	title = {High-resolution NMR structure and backbone dynamics of the Bacillus subtilis response regulator, SpoOF: Implications for phosphorylation and molecular recognition},
	journal = {Biochemistry},
	volume = {36},
	number = {33},
	year = {1997},
	note = {ISI Document Delivery No.: XR735Times Cited: 45Cited Reference Count: 78},
	month = {Aug},
	pages = {10015-10025},
	type = {Article},
	abstract = {NMR has been employed for structural and dynamic studies of the bacterial response regulator, SpoOF. This 124-residue protein is an essential component of the sporulation phosphorelay signal transduction pathway in Bacillus subtilis. Three-dimensional H-1, N-15, and C-13 experiments have been used to obtain full side chain assignments and the 1511 distance, 121 dihedral angle, and 80 hydrogen bonding restraints required for generating a family of structures (14 restraints per residue). The structures give a well-defined (alpha/beta)(5) fold for residues 4-120 with average rms deviations of 0.59 Angstrom for backbone heavy atoms and 1.02 Angstrom for all heavy atoms. Analyses of backbone N-15 relaxation measurements demonstrate relative rigidity in most regions of regular secondary structure with a generalized order parameter (S-2) Of 0.9 +/- 0.05 and a rotational correlation time (tau(m)) of 7.0 +/- 0.5 ns, Loop regions near the site of phosphorylation have higher than average rms deviation values and T-1/T-2 ratios suggesting significant internal motion or chemical exchange at these sites, Additionally, multiple conformers are observed for the beta 4-alpha 4 loop and beta-strand 5 region, These conformers may be related to structural changes associated with phosphorylation and also indicative of the propensity this recognition surface has for differential protein interactions. Comparison of SpoOF structural features to those of other response regulators reveals subtle differences in the orientations of secondary structure in the putative recognition surfaces and the relative charge distribution of residues surrounding the site of phosphorylation, These may be important in providing specificity for protein-protein interactions and for determining the lifetimes of the phosphorylated state.},
	keywords = {3-DIMENSIONAL STRUCTURE, BACTERIAL CHEMOTAXIS, C-13 MAGNETIZATION, C-13-ENRICHED PROTEINS, C-13-LABELED PROTEINS, ESCHERICHIA-COLI, MAGNESIUM-BINDING, NUCLEAR-MAGNETIC-RESONANCE, PROTEIN SECONDARY STRUCTURE, SIGNAL-TRANSDUCTION},
	isbn = {0006-2960},
	url = {<Go to ISI>://A1997XR73500007},
	author = {Feher, V. A. and Zapf, J. W. and Hoch, J. A. and Whiteley, J. M. and McIntosh, L. P. and Rance, M. and Skelton, N. J. and Dahlquist, F. W. and Cavanah, J.}
}
@article {3983,
	title = {The inhibition of glutamate racemase by D-N-hydroxyglutamate},
	journal = {Bioorganic \& Medicinal Chemistry Letters},
	volume = {7},
	number = {17},
	year = {1997},
	note = {ISI Document Delivery No.: XX507Times Cited: 20Cited Reference Count: 30},
	month = {Sep},
	pages = {2265-2270},
	type = {Article},
	abstract = {We report that D-N-hydroxyglutamate is ii competitive inhibitor of glutamate racemase (K-I=56 mu M). The compound acts as an alternate substrate and is converted into a-ketoglutarate and ammonia (K-M=57 mu M, k(cat)/K-M=3.2x10(3) M(-1)sec(-1)), An imine intermediate is likely the species causing the inhibition. L-N-hydroxyglutamate is a weak inhibitor and is slowly converted to alpha-ketoglutarate (k(cat)/K-M=30 M(-1)sec(-1)). (C) 1997 Elsevier Science Ltd.},
	keywords = {CLONING, DIAMINOPIMELIC ACID, EPIMERASE, ESCHERICHIA-COLI, GENE, L-ALANINE, LACTOBACILLUS, MURI, PEDIOCOCCUS-PENTOSACEUS, resistance},
	isbn = {0960-894X},
	url = {<Go to ISI>://A1997XX50700025},
	author = {Glavas, S. and Tanner, M. E.}
}
@inbook {3835,
	title = {Cellulose-binding domains - Versatile affinity tags for inexpensive large-scale purification, concentration, and immobilization of fusion proteins},
	booktitle = {Enzyme Engineering Xiii},
	series = {Annals of the New York Academy of Sciences},
	volume = {799},
	year = {1996},
	note = {ISI Document Delivery No.: BK03HTimes Cited: 6Cited Reference Count: 15Proceedings Paper13th International Enzyme Engineering ConferenceOCT 15-20, 1995SAN DIEGO, CALIFORNIAEngn Fdn, New York2 EAST 63RD ST, NEW YORK, NY 10021 USA},
	pages = {418-424},
	publisher = {New York Acad Sciences},
	organization = {New York Acad Sciences},
	address = {New York},
	keywords = {ESCHERICHIA-COLI, FIMI},
	isbn = {0077-89230-89766-981-9},
	url = {<Go to ISI>://000070949000067},
	author = {Tomme, P. and Gilkes, N. R. and Guarna, M. M. and Haynes, C. A. and Hasenwinkle, D. and Jervis, E. and Johnson, P. and McIntosh, L. and Warren, R. A. J. and Kilburn, D. G.},
	editor = {Dordick, J. S. and Russell, A. J.}
}
@article {3799,
	title = {Characterization of a buried neutral histidine residue in Bacillus circulans xylanase: NMR assignments, pH titration, and hydrogen exchange},
	journal = {Protein Science},
	volume = {5},
	number = {11},
	year = {1996},
	note = {ISI Document Delivery No.: VQ786Times Cited: 41Cited Reference Count: 63},
	month = {Nov},
	pages = {2319-2328},
	type = {Article},
	abstract = {Bacillus circulans xylanase contains two histidines, one of which (His 156) is solvent exposed, whereas the other (His 149) is buried within its hydrophobic core. His 149 is involved in a network of hydrogen bonds with an internal water and Ser 130, as well as a potential weak aromatic-aromatic interaction with Tyr 105. These three residues, and their network of interactions with the bound water, are conserved in four homologous xylanases. To probe the structural role played by His 149, NMR spectroscopy was used to characterize the histidines in BCX. Complete assignments of the H-1, C-13, and N-15 resonances and tautomeric forms of the imidazole rings were obtained from two-dimensional heteronuclear correlation experiments. An unusual spectroscopic feature of BCX is a peak near 12 ppm arising from the nitrogen bonded H-1(epsilon 2) of His 149. Due to its solvent inaccessibility and hydrogen bonding to an internal water molecule, the exchange rate of this proton (4.0 X 10(-5) s(-1) at pH* 7.04 and 30 degrees C) is retarded by > 10(6)-fold relative to an exposed histidine. The pK(a) of His 156 is unperturbed at similar to 6.5, as measured from the pH dependence of the N-15- and H-1-NMR spectra of BCX. In contrast, His 149 has a pK(a) < 2.3, existing in the neutral (NH)-H-epsilon 2 tautomeric state under all conditions examined. BCX unfolds at low pH and 30 degrees C, and thus His 149 is never protonated significantly in the context of the native enzyme. The structural importance of this buried histidine is confirmed by the destablizing effect of substituting a phenylalanine or glutamine at position 149 in BCX.},
	keywords = {ACTIVE-SITE, ALPHA-HELICES, AQUEOUS-SOLUTION, CHEMICAL-SHIFTS, ESCHERICHIA-COLI, GLYCOSYL HYDROLASES, H-1-NMR SPECTRUM, HYDROGEN-DEUTERIUM EXCHANGE, IMIDAZOLE, internal water, L-ALA-OH, NUCLEAR MAGNETIC-RESONANCE, pH titration, pK(alpha), PROTEIN HYDRATION, protein stability},
	isbn = {0961-8368},
	url = {<Go to ISI>://A1996VQ78600018},
	author = {Plesniak, L. A. and Connelly, G. P. and Wakarchuk, W. W. and McIntosh, L. P.}
}
@article {3805,
	title = {Enzymatic formation and release of a stable glycal intermediate: The mechanism of the reaction catalyzed by UDP-N-acetylglucosamine 2-epimerase},
	journal = {Journal of the American Chemical Society},
	volume = {118},
	number = {12},
	year = {1996},
	note = {ISI Document Delivery No.: UC380Times Cited: 19Cited Reference Count: 25},
	month = {Mar},
	pages = {3033-3034},
	type = {Article},
	keywords = {ACID, BACTERIOPHAGE-N4 ADSORPTION, biosynthesis, enterobacterial common antigen, ESCHERICHIA-COLI, MUTANTS, POSITIONAL ISOTOPE EXCHANGE, SEQUENCE},
	isbn = {0002-7863},
	url = {<Go to ISI>://A1996UC38000035},
	author = {Sala, R. F. and Morgan, P. M. and Tanner, M. E.}
}
@article {3708,
	title = {Interaction of soluble cellooligosaccharides with the N-terminal cellulose-binding domain of Cellulomonas fimi CenC .2. NMR and ultraviolet absorption spectroscopy},
	journal = {Biochemistry},
	volume = {35},
	number = {44},
	year = {1996},
	note = {ISI Document Delivery No.: VR098Times Cited: 68Cited Reference Count: 46},
	month = {Nov},
	pages = {13895-13906},
	type = {Article},
	abstract = {The N-terminal cellulose-binding domain (CBDN1) from Cellulomonas fimi beta-1,4-glucanase CenC binds amorphous but not crystalline cellulose. To investigate the structural and thermodynamic bases of cellulose binding, NMR and difference ultraviolet absorbance spectroscopy were used in parallel with calorimetry (Tomme, P., Creagh, A. L., Kilburn, D. G., \& Haynes, C. A., (1996) Biochemistry 35, 13885-13894] to characterize the interaction of soluble cellooligosaccharides with CBDN1 Association constants, determined from the dependence of the amide H-1 and N-15 chemical shifts of CBDN1 upon added sugar, increase from 180 +/- 60 M(-1) for cellotriose to 4 200 +/- 720 M(-1) for cellotetraose, 34 000 +/- 7 600 M(-1) for cellopentaose, and an estimate of 50 000 M(-1) for cellohexaose. This implies that the CBDN1 cellulose-binding site spans approximately five glucosyl units, On the basis of the observed patterns of amide chemical shift changes, the cellooligosaccharides bind along a five-stranded beta-sheet that forms a concave face of the jelly-roll beta-sandwich structure of CBDN1. This beta-sheet contains a strip of hydrophobic side chains flanked on both sides by polar residues, NMR and difference ultraviolet absorbance measurements also demonstrate that tyrosine, but not tryptophan, side chains may be involved in oligosaccharide binding. These results lead to a model in which CBDN1 interacts with soluble cellooligosaccharides and, by inference, with single polysaccharide chains in regions of amorphous cellulose, primarily through hydrogen bonding to the equatorial hydroxyl groups of the pyranose rings. Van der against the apolar side chains may augment binding. CBDN1 stands in marked contrast to previously characterized CBDs that absorb to crystalline cellulose via a flat binding surface dominated by exposed aromatic rings.},
	keywords = {BACKBONE H-1, CHEMICAL-SHIFTS, ESCHERICHIA-COLI, EXPRESSION, HIGH-LEVEL, NUCLEAR-MAGNETIC-RESONANCE, PROTEIN, REESEI CELLOBIOHYDROLASE-I, SEQUENCE, TRICHODERMA-REESEI, TRYPTOPHAN RESIDUES},
	isbn = {0006-2960},
	url = {<Go to ISI>://A1996VR09800005},
	author = {Johnson, P. E. and Tomme, P. and Joshi, M. D. and McIntosh, L. P.}
}
@article {3832,
	title = {Phosphinate inhibitors of the D-glutamic acid-adding enzyme of peptidoglycan biosynthesis},
	journal = {Journal of Organic Chemistry},
	volume = {61},
	number = {5},
	year = {1996},
	note = {ISI Document Delivery No.: TZ997Times Cited: 66Cited Reference Count: 31},
	month = {Mar},
	pages = {1756-1760},
	type = {Article},
	abstract = {We report the synthesis and initial evaluation of the first effective inhibitors of the D-glutamic acid-adding enzyme (UDP-N-acetylmuramoyl-L-alanine:D-glutamate ligase or MurD). This enzyme plays a key role in bacterial peptidoglycan biosynthesis and is therefore a target for antibiotic design. Phosphinic acid 3 is a dipeptide analog linked to uridine diphosphate by a hydrophobic spacer. It is a good inhibitor of the enzyme (IC50 = 0.68 mu M) as it closely resembles the tetrahedral intermediate that is presumed to form in the ligation reaction. Compound 4 lacks the terminal UMP group, and compound 5 lacks both the linker and UDP functionalities. These are less effective inhibitors of the enzyme with IC50 values of 29 mu M and > 1 mM, respectively. Preincubation of the enzyme in the presence of inhibitor 3 and ATP does not result in irreversible inhibition or in the formation of a slowly decomplexing species, suggesting that the phosphinic acid is not phosphorylated in the active site.},
	keywords = {(AMINOALKYL)PHOSPHINATE, ATP, D-ALANINE LIGASE, ESCHERICHIA-COLI, INACTIVATION, MECHANISM, PHOSPHINOTHRICIN, PURIFICATION, RAPID-QUENCH, SYNTHETASE},
	isbn = {0022-3263},
	url = {<Go to ISI>://A1996TZ99700030},
	author = {Tanner, M. E. and Vaganay, S. and vanHeijenoort, J. and Blanot, D.}
}
@article {3762,
	title = {The pK(a) of the general acid/base carboxyl group of a glycosidase cycles during catalysis: A C-13-NMR study of Bacillus circuluns xylanase},
	journal = {Biochemistry},
	volume = {35},
	number = {31},
	year = {1996},
	note = {ISI Document Delivery No.: VB211Times Cited: 149Cited Reference Count: 43},
	month = {Aug},
	pages = {9958-9966},
	type = {Article},
	abstract = {The 20 kDa xylanase from Bacillus circulans carries out hydrolysis of xylan via a two-step mechanism involving a covalent glycosyl-enzyme intermediate. In this double-displacement reaction, Glu78 functions as a nucleophile to form the intermediate, while Glu172 acts as a general acid catalyst during glycosylation, protonating the departing aglycone, and then as a general base during deglycosylation, deprotonating the attacking water, The dual role of Glu172 places specific demands upon its ionization states and hence pK(a) values. C-13-NMR titrations of xylanase, labeled with [delta-C-13]glutamic acid, have revealed pK(a) values of 4.6 and 6.7 for Glu78 and Glu172, respectively. These agree well with the apparent pK(a) values obtained from a study of the pH dependence of k(cat)/K-m and demonstrate that, at the enzyme{\textquoteright}s pH optimum of 5.7, the nucleophile Glu78 is deprotonated and the general acid Glu172 initially protonated. Remarkably, the pK(a) for Glu172 drops to 4.2 in a trapped covalent glycosyl-enzyme intermediate, formed by reaction with 2{\textquoteright},4{\textquoteright}-dinitrophenyl 2-deoxy-2-fluoro-beta-xylobioside [Miao et al. (1994) Biochemistry 33, 7027-7032], A similar pK(a) is measured for Glu172 when a glutamine is present at position 78. This large decrease in pK(a) of similar to 2.5 units is consistent with the role of Glu172 as a general base catalyst in the deglycosylation step and appears to be a consequence of both reduced electrostatic repulsion due to neutralization of Glu78 and a conformational change in the protein. Such {\textquoteright}{\textquoteright}pK(a) cycling{\textquoteright}{\textquoteright} during catalysis is likely to be a common phenomenon in glycosidases.},
	keywords = {ACTIVE-SITE RESIDUES, AMINO-ACIDS, beta-glucosidase, ELECTROSTATIC INTERACTIONS, ESCHERICHIA-COLI, IDENTIFICATION, LYSOZYME, MECHANISMS, NUCLEAR-MAGNETIC-RESONANCE, PROTEINS},
	isbn = {0006-2960},
	url = {<Go to ISI>://A1996VB21100003},
	author = {McIntosh, L. P. and Hand, G. and Johnson, P. E. and Joshi, M. D. and Korner, M. and Plesniak, L. A. and Ziser, L. and Wakarchuk, W. W. and Withers, S. G.}
}
@article {3621,
	title = {Probing the role of tryptophan residues in a cellulose-binding domain by chemical modification},
	journal = {Protein Science},
	volume = {5},
	number = {11},
	year = {1996},
	note = {ISI Document Delivery No.: VQ786Times Cited: 41Cited Reference Count: 34},
	month = {Nov},
	pages = {2311-2318},
	type = {Article},
	abstract = {The cellulose-binding domain (CBDCex) of the mixed function glucanase-xylanase Cex from Cellulomonas fimi contains five tryptophans, two of which are located within the p-barrel structure and three exposed on the surface (Xu GY et al., 1995, Biochemistry 34:6993-7009). Although all five tryptophans can be oxidized by N-bromosuccinimide (NBS), stopped-flow measurements show that three tryptophans react faster than the other two. NMR analysis during the titration of CBDCex with NBS shows that the tryptophans on the surface of the protein are fully oxidized before there is significant reaction with the two buried tryptophans. Additionally, modification of the exposed tryptophans does not affect the conformation of the backbone of CBDCex, whereas complete oxidation of all five tryptophans denatures the polypeptide. The modification of the equivalent of one and two tryptophans by NBS reduces binding of CBDCex to cellulose by 70\% and 90\%, respectively. This confirms the direct role of the exposed aromatic residues in the binding of CBDCex to cellulose. Although adsorption to cellulose does afford some protection against NBS, as evidenced by the increased quantity of NBS required to oxidize all of the tryptophan residues, the polypeptide can still be oxidized completely when adsorbed. This suggests that, whereas the binding appears to be irreversible overall [Ong E et al., 1989, Bio/Technology 7:604-607], each of the exposed tryptophans interacts reversibly with cellulose.},
	keywords = {absorbance spectroscopy, ACTIVE-SITE, CELLOBIOHYDROLASE-I, cellulose-binding, ENDOGLUCANASE, ESCHERICHIA-COLI, FIMI, fluorescence spectroscopy, N-bromosuccinimide, NMR, NUCLEAR-MAGNETIC-RESONANCE, SCHIZOPHYLLUM-COMMUNE, SPECTROSCOPY, TRICHODERMA-REESEI, XYLANASE-A},
	isbn = {0961-8368},
	url = {<Go to ISI>://A1996VQ78600017},
	author = {Bray, M. R. and Johnson, P. E. and Gilkes, N. R. and McIntosh, L. P. and Kilburn, D. G. and Warren, R. A. J.}
}
@article {3480,
	title = {AN AUTOCLAVABLE GLUCOSE BIOSENSOR FOR MICROBIAL FERMENTATION MONITORING AND CONTROL},
	journal = {Biotechnology and Bioengineering},
	volume = {46},
	number = {6},
	year = {1995},
	note = {ISI Document Delivery No.: QY630Times Cited: 16Cited Reference Count: 49},
	month = {Jun},
	pages = {514-524},
	type = {Article},
	abstract = {The design, construction, and characterization of a prototype-regenerable glucose biosensor based on the reversible immobilization of glucose oxidase (GOx) using cellulose binding domain (CBD) technology is described. GOx, chemically linked to CBD, is immobilized by binding to a cellulose matrix on the sensor-indicating electrode. Enzyme immobilization can be reversed by perfusing the cellulose matrix with a suitable eluting solution. An autoclavable sensor membrane system is employed which is shown to be practical for use in real microbial fermentations. The prototype glucose biosensor was used without failure or deterioration during fed-batch fermentations of Escherichia coli reaching a maximum cell density of 85 g (dry weight)/L. Medium glucose concentration based on sensor output correlated closely with off-line glucose analysis and was controlled manually at 0.44 +/- 0.2 g/L for 2 h based on glucose sensor output. The sensor enzyme component could be eluted and replaced without interrupting the fermentation. To our knowledge, no other in situ biosensor has been used for such an extended period of time in such a high-cell-density fermentation. (C) 1995 John Wiley \& Sons, Inc.},
	keywords = {(CBD), AMPEROMETRIC BIOSENSORS, BATCH, BIOSENSOR, CELLULOSE BINDING DOMAIN, CELLULOSE-BINDING DOMAIN, ELECTROCHEMICAL DETECTOR, ENZYME ELECTRODE, ESCHERICHIA-COLI, FERMENTATION MONITORING, FLOW-INJECTION ANALYSIS, GLUCOSE BIOSENSOR, GLUCOSE OXIDASE, OPTIMIZATION, OXIDASE ELECTRODE, OXYGEN},
	isbn = {0006-3592},
	url = {<Go to ISI>://A1995QY63000003},
	author = {Phelps, M. R. and Hobbs, J. B. and Kilburn, D. G. and Turner, R. F. B.}
}
@article {3175,
	title = {THE SYNTHESIS AND STABILITY OF AZIRIDINO-GLUTAMATE, AN IRREVERSIBLE INHIBITOR OF GLUTAMATE RACEMASE},
	journal = {Tetrahedron Letters},
	volume = {35},
	number = {24},
	year = {1994},
	note = {ISI Document Delivery No.: NR716Times Cited: 37Cited Reference Count: 17},
	month = {Jun},
	pages = {4073-4076},
	type = {Article},
	abstract = {Aziridino-glutamate (2-(2-carboxyethyl)aziridine-2-carboxylic acid, (+/-)4) was synthesized by heating alpha-fluoromethylglutamate in base. In neutral solution, 4 was shown to cyclize to the gamma-lactone 5 with a half life of 4 minutes. Aziridino-glutamate was shown to irreversibly inactivate glutamate racemase by alkylating an active site cysteine residue, Electrospray mass spectrometry was used to establish that a covalent bond had famed and that this bond protects one of the enzyme{\textquoteright}s two cysteine residues from reacting with iodoacetate under denaturing conditions.},
	keywords = {ACID, EPIMERASE, ESCHERICHIA-COLI, MECHANISM, PEDIOCOCCUS-PENTOSACEUS},
	isbn = {0040-4039},
	url = {<Go to ISI>://A1994NR71600007},
	author = {Tanner, M. E. and Miao, S. C.}
}
@article {3144,
	title = {TECHNOLOGY FOR REGENERABLE BIOSENSOR PROBES BASED ON ENZYME CELLULOSE-BINDING DOMAIN CONJUGATES},
	journal = {Biotechnology Progress},
	volume = {10},
	number = {4},
	year = {1994},
	note = {ISI Document Delivery No.: PC847Times Cited: 9Cited Reference Count: 39},
	month = {Jul-Aug},
	pages = {433-440},
	type = {Article},
	abstract = {The application of enzyme-based biosensors for on-line bioprocess monitoring and control has been slowed by problems relating to the in situ sterilizability of the probe and the stability of the enzyme component. A novel technology with the potential to address both of these difficulties is presented here, The approach is based on the reversible immobilization of enzymes conjugated with the cellulose binding domain (CBD) of cellulases from Cellulomonas fimi. A regenerable biosensor electrode can be configured with a cellulose matrix onto which the enzyme-CBD conjugate can be repeatedly loaded (bound by the CBD) and subsequently eluted by perfusing the cellulose matrix with the appropriate solution. Glucose oxidase (GOx) conjugated to CBD with glutaraldehyde was used in an experimental glucose biosensor to demonstrate the feasibility of multiple cycles of loading and elution of the conjugate. Michaelis-Menten enzyme kinetics provided an empirical model for the calibration of the experimental biosensor. The development of a computer-controlled prototype glucose biosensor and a fermentation monitoring system based on this approach is discussed.},
	keywords = {CLONING, electrode, ESCHERICHIA-COLI, EXOGLUCANASE, FIMI, GENE, GLUCOSE-OXIDASE, IMMOBILIZATION, ONLINE DETERMINATION, SEQUENCE},
	isbn = {8756-7938},
	url = {<Go to ISI>://A1994PC84700014},
	author = {Phelps, M. R. and Hobbs, J. B. and Kilburn, D. G. and Turner, R. F. B.}
}
