@article {1368,
	title = {Calcium ion exchange in crystalline gelsolin},
	journal = {Journal of Molecular Biology},
	volume = {357},
	number = {3},
	year = {2006},
	note = {ISI Document Delivery No.: 030IYTimes Cited: 6Cited Reference Count: 24},
	month = {Mar},
	pages = {773-782},
	type = {Article},
	abstract = {Gelsolin is a calcium and pH-sensitive modulator of actin filament length. Here, we use X-ray crystallography to examine the extraction and exchange of calcium ions from their binding sites in different crystalline forms of the activated N and C-terminal halves of gelsolin, G1-G3 and G4-G6, respectively. We demonstrate that the combination of calcium and low pH activating conditions do not induce conformational changes in G4-G6 beyond those elicited by calcium alone. EGTA is able to remove calcium ions bound to the type I and type II metal ion-binding sites in G4-G6. Constrained by crystal contacts and stabilized by interdomain interaction surfaces, the gross structure of calcium-depleted G4-G6 remains that of the activated form. However, high-resolution details of changes in the ion-binding sites may represent the initial steps toward restoration of the arrangement of domains found in the calcium-free inactive form of gelsolin in solution. Furthermore, bathing crystals with the trivalent calcium ion mimic, Tb3+, results in anomalous scattering data that permit unequivocal localization of terbium ions in each of the proposed type I and type II ion-binding sites of both halves of gelsolin. In contrast to predictions based on solution studies, we find that no calcium ion is immune to exchange. (c) 2006 Elsevier Ltd. All rights reserved.},
	keywords = {actin, ACTIN MONOMER, ACTIVATION, apoptosis, BINDING-SITE, C-TERMINAL HALF, calcium activation, COMPLEX, CONFORMATIONAL CHANGE, DOMAINS, ELECTRON-DENSITY MAPS, gelsolin, IDENTIFICATION, MECHANISMS, protein crystallography},
	isbn = {0022-2836},
	url = {<Go to ISI>://000236629300008},
	author = {Chumnarnsilpa, S. and Loonchanta, A. and Xue, B. and Choe, H. and Urosev, D. and Wang, H. and Lindberg, U. and Burtnick, L. D. and Robinson, R. C.}
}
@article {896,
	title = {Inhibition of Chk1 by the G(2) DNA damage checkpoint inhibitor isogranulatimide},
	journal = {Molecular Cancer Therapeutics},
	volume = {3},
	number = {10},
	year = {2004},
	note = {ISI Document Delivery No.: 862KBTimes Cited: 40Cited Reference Count: 40},
	month = {Oct},
	pages = {1221-1227},
	type = {Article},
	abstract = {Inhibitors of the G(2) DNA damage checkpoint can selectively sensitize cancer cells with mutated p53 to killing by DNA-damaging agents. Isogranulatimide is a G2 checkpoint inhibitor containing a unique indole/maleimide/ imidazole skeleton identified in a phenotypic cell-based screen; however, the mechanism of action of isogranulatimide is unknown. Using natural and synthetic isogranulatimide analogues, we show that the imide nitrogen and a basic nitrogen at position 14 or 15 in the imidazole ring are important for checkpoint inhibition. Isogranulatimide shows structural resemblance to the aglycon of UCN-01, a potent bisindolemaleimide inhibitor of protein kinase Cbeta (IC50, 0.001 mumol/L) and of the checkpoint kinase Chk1 (IC50, 0.007 mumol/L). In vitro kinase assays show that isogranulatimide inhibits Chk1 (IC50, 0.1 mumol/L) but not protein kinase Cbeta. Of 13 additional protein kinases tested, isogranulatimide significantly inhibits only glycogen synthase kinase-3beta (IC50, 0.5 mumol/L). We determined the crystal structure of the Chk1 catalytic domain complexed with isogranulatimicle. Like UCN-01, isogranulatimide binds in the ATP-binding pocket of Chk1 and hydrogen bonds with the backbone carbonyl oxygen of Glu(85) and the amide nitrogen Of Cys(87). Unlike UCN-01, the basic N15 of isogranulatimide interacts with Glu(17), causing a conformation change in the kinase glycine-rich loop that may contribute importantly to inhibition. The mechanism by which isogranulatimide inhibits Chk1 and its favorable kinase selectivity profile make it a promising candidate for modulating checkpoint responses in tumors for therapeutic benefit.},
	keywords = {7-HYDROXYSTAUROSPORINE UCN-01, ACTIVATION, CANCER, CELL-CYCLE, DEPENDENT PROTEIN-KINASE, IDENTIFICATION, MECHANISMS, PHOSPHORYLATION, SPECIFICITY, SUBSTRATE},
	isbn = {1535-7163},
	url = {<Go to ISI>://000224488400006},
	author = {Jiang, X. X. and Zhao, B. G. and Britton, R. and Lim, L. Y. and Leong, D. and Sanghera, J. S. and Zhou, B. B. S. and Piers, E. and Andersen, R. J. and Roberge, M.}
}
@article {671,
	title = {HTI-286, a synthetic analogue of the tripeptide hemiasterlin, is a potent antimicrotubule agent that circumvents P-glycoprotein-mediated resistance in vitro and in vivo},
	journal = {Cancer Research},
	volume = {63},
	number = {8},
	year = {2003},
	note = {ISI Document Delivery No.: 668TETimes Cited: 57Cited Reference Count: 32},
	month = {Apr},
	pages = {1838-1845},
	type = {Article},
	abstract = {Hemiasterlin is a natural product derived from marine sponges that, like other structurally diverse peptide-like molecules, binds to the Vincapeptide site in tubulin, disrupts normal microtubule dynamics, and, at stoichiometric amounts, depolymerizes microtubules. Total synthesis of hemiasterlin and its analogues has been accomplished, and optimal pharmacological features of the series have been explored. The biological profile of one analogue, HTI-286, was studied here. HTI-286 inhibited the polymerization of purified tubulin, disrupted microtubule organization in cells, and induced mitotic arrest, as well as apoptosis. HTI-286 was a potent inhibitor of proliferation (mean IC50 = 2.5 +/- 2.1 nm in 18 human tumor cell lines) and had substantially less interaction with multidrug resistance protein (P-glycoprotein) than currently used antimicrotubule agents, including paclitaxel, docetaxel, vinorelbine, or vinblastine. Resistance to HTI-286 was not detected in cells overexpressing the drug transporters MRP1 or MXR. In athymic mice implanted with human tumor xenografts, HTI-286 administered i.v. in saline inhibited the growth of numerous human tumors derived from carcinoma of the skin, breast, prostate, brain, and colon. Marked tumor regression was observed when used on established tumors that were >1 gram in size. Moreover, HTI-286 inhibited the growth of human tumor xenografts (e.g., HCT-15, DLD-1, MX-1W, and KB-8-5) where paclitaxel and vincristine were ineffective because of inherent or acquired resistance associated with P-glycoprotein. Efficacy was also achieved with p.o. administration of HTI-286. These data suggest that HTI-286 has excellent preclinical properties that may translate into superior clinical activity, as well as provide a useful synthetic reagent to probe the drug contact sites of peptide-like molecules that interact with tubulin.},
	keywords = {ADRIAMYCIN, BETA-TUBULIN, CANCER, CARCINOMA-CELLS, CYTOTOXIC PEPTIDES, DOLASTATIN ANALOG, DRUG-RESISTANCE, EXPRESSION, MECHANISMS, MULTIDRUG-RESISTANCE},
	isbn = {0008-5472},
	url = {<Go to ISI>://000182308600021},
	author = {Loganzo, F. and Discafani, C. M. and Annable, T. and Beyer, C. and Musto, S. and Hari, M. and Tan, X. Z. and Hardy, C. and Hernandez, R. and Baxter, M. and Singanallore, T. and Khafizova, G. and Poruchynsky, M. S. and Fojo, T. and Nieman, J. A. and Ayral-Kaloustian, S. and Zask, A. and Andersen, R. J. and Greenberger, L. M.}
}
@article {5102,
	title = {Bis(mercapto) and hydrido(thiolate) complexes of Ru(II)-dppm (dppm = Ph2PCH2PPh2)},
	journal = {Inorganica Chimica Acta},
	volume = {320},
	number = {1-2},
	year = {2001},
	note = {ISI Document Delivery No.: 472CETimes Cited: 6Cited Reference Count: 33},
	month = {Aug},
	pages = {184-189},
	type = {Article},
	abstract = {From a mixture of cis- and trans-Ru(SH)(2)(dppm)(2) (4), formed from reaction of H2S with trans-Ru(H)Cl(dppm)(2) (2), a crystal of cis-4 has been isolated and its structure determined by X-ray analysis. The mercapto protons are located within the centrosymmetric structure, although the S-atoms are partially disordered (S - H similar to 1.06 Angstrom). The thiolate complexes, trans-Ru(H)SR(dppm)(2) (R = Ph, 5a; C6F5, 5b), have been isolated from reaction of trans-2 with 1 equiv. of RSH. trans-Ru(H)SH(dppm)(2) (3) has been isolated from reaction of H2S with a mixture of cis- and trans-Ru(H)(2)(dppm)(2) (1). An improved synthetic route for 1 is presented. (C) 2001 Elsevier Science B.V. All rights reserved.},
	keywords = {CHEMISTRY, COMPLEXES, crystal structures, CRYSTAL-STRUCTURE, DERIVATIVES, DINUCLEAR RHODIUM COMPLEXES, hydrido complexes, HYDROFORMYLATION, MECHANISMS, MERCAPTO, PHOSPHINE COMPLEXES, ruthenium complexes, RUTHENIUM(II), THIOLATO, WATER},
	isbn = {0020-1693},
	url = {<Go to ISI>://000170965000025},
	author = {Khorasani-Motlagh, M. and Safari, N. and Pamplin, C. B. and Patrick, B. O. and James, Brian R.}
}
@article {5098,
	title = {Dissecting the electrostatic interactions and pH-dependent activity of a family 11 glycosidase},
	journal = {Biochemistry},
	volume = {40},
	number = {34},
	year = {2001},
	note = {ISI Document Delivery No.: 466CYTimes Cited: 56Cited Reference Count: 50},
	month = {Aug},
	pages = {10115-10139},
	type = {Article},
	abstract = {Previous studies of the low molecular mass family 11 xylanase from Bacillus circulans show that the ionization state of the nucleophile (GIu78, pK(a) 4.6) and the acid/base catalyst (Glu 172, pK(a) 6.7) gives rise to its pH-dependent activity profile. Inspection of the crystal structure of BCX reveals that Glu78 and Glu172 are in very similar environments and are surrounded by several chemically equivalent and highly conserved active site residues. Hence, there are no obvious reasons why their apparent pKa values are different. To address this question, a mutagenic approach was implemented to determine what features establish the pKa values (measured directly by C-13 NMR and indirectly by pH-dependent activity profiles) of these two catalytic carboxylic acids. Analysis of several BCX variants indicates that the ionized form of Glu78 is preferentially stabilized over that of Glu 172 in part by stronger hydrogen bonds contributed by two well-ordered residues, namely, Tyr69 and Gln127. In addition, theoretical pKa calculations show that Glu78 has a lower pKa value than Glu 172 due to a smaller desolvation energy and more favorable background interactions with permanent partial charges and ionizable groups within the protein. The pKa value of Glu172 is in turn elevated due to electrostatic repulsion from the negatively charged glutamate at position 78. The results also indicate that all of the conserved active site residues act concertedly in establishing the pKa values of Glu78 and Glu 172, with no particular residue being singly more important than any of the others. In general, residues that contribute positive charges and hydrogen bonds serve to lower the pKa values of Glu78 and Glu172. The degree to which a hydrogen bond lowers a pKa value is largely dependent on the length of the hydrogen bond (shorter bonds lower pKa values more) and the chemical nature of the donor (COOH > OH > CONH2). In contrast, neighboring carboxyl groups can either lower or raise the pKa values of the catalytic glutamic acids depending upon the electrostatic linkage of the ionization constants of the residues involved in the interaction. While the pH optimum of BCX can be shifted from -1.1 to +0.6 pH units by mutating neighboring residues within the active site, activity is usually compromised due to the loss of important ground and/or transition state interactions. These results suggest that the pH optima of an enzyme might be best engineered by making strategic amino acid substitutions, at positions outside of the "core" active site, that electrostatically influence catalytic residues without perturbing their immediate structural environment.},
	keywords = {ASSIGNMENTS, BACILLUS-CIRCULANS XYLANASE, CATALYSIS, GLYCOSYL-ENZYME INTERMEDIATE, KINETIC-ANALYSIS, MASS-SPECTROMETRY, MECHANISMS, NMR, PK(A), PROTEIN, SITE NUCLEOPHILE, structures},
	isbn = {0006-2960},
	url = {<Go to ISI>://000170627800014},
	author = {Joshi, M. D. and Sidhu, G. and Nielsen, J. E. and Brayer, G. D. and Withers, S. G. and McIntosh, L. P.}
}
@article {5226,
	title = {Reaction of human myoglobin and peroxynitrite: Characterizing biomarkers for myoglobin-derived oxidative stress},
	journal = {Biochemical and Biophysical Research Communications},
	volume = {286},
	number = {2},
	year = {2001},
	note = {ISI Document Delivery No.: 465TNTimes Cited: 11Cited Reference Count: 32},
	month = {Aug},
	pages = {352-356},
	type = {Article},
	abstract = {Mixtures of human myoglobin (Mb) (or the Y103F variant of human Mb), authentic peroxynitrite (ONOO-, ONOO-:protein 2 mol/mol), and 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) gave radicals adducts at cysteine-110 (DMPO-C110) that are detected directly by electron paramagnetic magnetic spectroscopy (EPR). DMPO-C110 was detected exclusively over a range of DMPO concentrations (DMPO:protein ratios 25-100 mol/mol). Treatment of human Mb (or Y103F Mb) with the ONOO- generator 5-amino-3-(4-morpholinyl)-1,2,3-oxadiazolium (SIN-1) chloride (ONOO-: protein 5 mol/mol) yielded a cross-linked Mb dimer as judged by SDS-PAGE analyses. Addition of DMPO or carbonate effectively eliminated the cross-linked product. Mass analyses of samples containing human Mb (or Y103F Mb), carbonate, and ONOO- indicated that nitration occurs exclusively at Y103. Thus, reaction of human Mb and ONOO- yields specific products that depend on the presence or absence of physiological concentrations of carbonate. These products may serve as biomarkers for the participation of Mb-derived radicals in the oxidative damage associated with myocardial reperfusion injury. (C) 2001 Academic Press.},
	keywords = {ARRHYTHMIAS, free radical, GENERATION, HYDROGEN-PEROXIDE, ischaemia reperfusion injury, MECHANISMS, MYOGLOBIN, NITRATION, NITRIC-OXIDE, nitro-tyrosine, peroxynitrite, protein-thiyl radical, radicals, REPERFUSION INJURY, SITE-DIRECTED MUTAGENESIS, SUPEROXIDE, SYSTEMS},
	isbn = {0006-291X},
	url = {<Go to ISI>://000170606200020},
	author = {Witting, P. K. and Mauk, A. G. and Douglas, D. J. and Stocker, R.}
}
@article {4271,
	title = {Complications in investigations of the swelling of hydrogel matrices due to the presence of trapped gas},
	journal = {Journal of Controlled Release},
	volume = {52},
	number = {1-2},
	year = {1998},
	note = {ISI Document Delivery No.: ZC530Times Cited: 13Cited Reference Count: 11},
	month = {Mar},
	pages = {221-225},
	type = {Article},
	abstract = {In recent studies, NMR imaging has been used to investigate the swelling of hydroxypropylmethylcellulose (HPMC) tablets and to determine polymer concentration distributions in the swollen matrix. The total amount of polymer in the system was computed from these distributions and was up to 35\% greater than the known weight of HPMC in the tablet. This deviation was traced to the presence of air bubbles in the swollen matrix which occupied a significant volume previously assumed to be occupied by polymer and water. When the air in the tablet was removed by vacuum, the swollen gel contained no evidence of air bubbles and the calculated total polymer weights from the HPMC distributions were equal to the amount of HPMC in the tablet. (C) 1998 Elsevier Science B.V.},
	keywords = {BEHAVIOR, CONTROLLED RELEASE, DRUG-RELEASE, GEL, HPMC TABLETS, hydrophilic matrix tablet, hydroxypropylmethylcellulose, IMAGING METHOD, LAYER, MECHANISMS, NMR imaging, RELEASE DOSAGE FORMS, swelling},
	isbn = {0168-3659},
	url = {<Go to ISI>://000072589600022},
	author = {Fyfe, C. A. and Blazek, A. I.}
}
@article {4447,
	title = {Pre-steady state kinetic analysis of an enzymatic reaction monitored by time-resolved electrospray ionization mass spectrometry},
	journal = {Biochemistry},
	volume = {37},
	number = {21},
	year = {1998},
	note = {ISI Document Delivery No.: ZR717Times Cited: 73Cited Reference Count: 53},
	month = {May},
	pages = {7664-7669},
	type = {Article},
	abstract = {For the first time, the new technique of time-resolved electrospray ionization mass spectrometry (ESI-MS) has been used to accurately measure the pre-steady state kinetics of an enzymatic reaction by monitoring a transient enzyme intermediate. The enzyme used to illustrate this approach, Bacillus circulans xylanase, is a retaining glycosidase that hydrolyzes xylan or beta-xylobiosides through a double-displacement mechanism involving a covalent xylobiosyl-enzyme intermediate. A low steady state level of this intermediate formed during the hydrolysis of 2,5-dinitrophenyl beta-D-xylobioside was detected by time-resolved ESI-MS. The low concentration of this intermediate and its rate of formation did not permit pre-steady state kinetic analysis. By contrast, the covalent intermediate accumulates fully when the Tyr80Phe mutant hydrolyzes the same substrate. Using time-resolved ESI-MS, the pre-steady state kinetic parameters for the formation of the covalent intermediate in the mutant xylanase have been determined. The kinetic data are in agreement with those determined by monitoring the release of 2,5-dinitrophenol with stopped-flow W-vis spectroscopy. This demonstrates that time-resolved ESI-MS can be used to accurately monitor the pre-steady state kinetics of enzymatic reactions, with the advantage of identifying transient enzyme intermediates by their mass.},
	keywords = {ACTIVE-SITE NUCLEOPHILE, AMINO-ACID, BACILLUS-CIRCULANS XYLANASE, beta-glucosidase, CELLULASES, CYTOCHROME-C, GAS-PHASE, IDENTIFICATION, inhibitors, MECHANISMS},
	isbn = {0006-2960},
	url = {<Go to ISI>://000074006700002},
	author = {Zechel, D. L. and Konermann, L. and Withers, S. G. and Douglas, D. J.}
}
@article {4141,
	title = {Dipole-induced ordering in nematic liquid crystals fact or fiction?},
	journal = {Chemical Physics Letters},
	volume = {281},
	number = {1-3},
	year = {1997},
	note = {ISI Document Delivery No.: YP239Times Cited: 18Cited Reference Count: 35},
	month = {Dec},
	pages = {199-206},
	type = {Article},
	abstract = {Similar size and shape molecules with different electric multipoles are used to investigate effects of dipole and quadrupole interactions on the average orientation of solutes in nematic liquid crystals. Permanent dipoles have a negligible influence on solute orientation. Order parameters predicted from strong, short-range repulsive forces coupled with interactions between the solute quadrupole and the average electric field gradient felt by the solute [EFG] are consistent with experimental values. Calculated [EFG]{\textquoteright}s are the same sign and similar magnitude to those determined previously from D-2 and HD. For the nematic mixture 55wt\% ZLI 1132 in EBBA, the contribution to solute ordering from long-range electrostatic interactions is negligible. (C) 1997 Elsevier Science B.V.},
	keywords = {deuterium, ELECTRIC-DIPOLE, MECHANISMS, MOLECULAR-HYDROGEN, NMR-SPECTRA, orientational order, POTENTIALS, QUADRUPOLE-MOMENTS, SOLUTES, SOLVENTS},
	isbn = {0009-2614},
	url = {<Go to ISI>://000071256600030},
	author = {Syvitski, R. T. and Burnell, E. E.}
}
@article {3978,
	title = {Investigation of hydrogel formation from hydroxypropylmethylcellulose (HPMC) by NMR spectroscopy and NMR imaging techniques},
	journal = {Macromolecules},
	volume = {30},
	number = {20},
	year = {1997},
	note = {ISI Document Delivery No.: YA289Times Cited: 54Cited Reference Count: 21},
	month = {Oct},
	pages = {6230-6237},
	type = {Article},
	abstract = {NMR imaging has been used to investigate the in situ swelling behavior of 2-hydroxypropylmethylcellulose (HPMC) tablets in a sample geometry chosen for the simplicity of its diffusion behavior. Preliminary H-1 NMR spectroscopy experiments were performed on equilibrated mixtures of HPMC and water. From these, the dependence of the H-1 T-1 and T-2 relaxation parameters of the water protons with respect to HPMC weight percent were obtained. Further analysis of the T-2 values and H-1 z-spectroscopic data revealed that as the polymer concentration was increased from 10\% to 20\% w/w HPMC, the polymer mobility decreased substantially. One-dimensional NMR imaging of H-1 in the swelling tablet system was used to monitor the movement of water into the polymer and to calculate the T-2 parameters across the system. HPMC weight percents were calculated from these T-2 values using the previously determined calibration. HPMC distributions were determined for two tablet thicknesses. Similar swelling behavior was observed for both thicknesses at early times prior to the thinner tablet becoming completely hydrated.},
	keywords = {ABSORPTION, BEHAVIOR, DIFFUSION, DRUG-RELEASE, GEL LAYER, MECHANISMS, microscopy, PENETRATION, RELEASE DOSAGE FORMS, TABLETS},
	isbn = {0024-9297},
	url = {<Go to ISI>://A1997YA28900036},
	author = {Fyfe, C. A. and Blazek, A. I.}
}
@article {3919,
	title = {Tritium nuclear magnetic resonance study of T-2, HT, and DT dissolved in nematic solvents},
	journal = {Physical Review E},
	volume = {55},
	number = {1},
	year = {1997},
	note = {ISI Document Delivery No.: WD545Times Cited: 5Cited Reference Count: 25Part A},
	month = {Jan},
	pages = {496-503},
	type = {Article},
	abstract = {A tritium nuclear magnetic resonance study is carried out on the T-2, HT, and DT isotopomers of dihydrogen dissolved in various nematic phases, including a zero-electric-field-gradient mixture. Ab initio calculations are performed to reproduce the observed dipolar couplings. Within the framework of the {\textquoteright}{\textquoteright}mean-field{\textquoteright}{\textquoteright} approximation, the results provide support for a picture in which two independent contributions to the solute orientation can be distinguished. One contribution involves a liquid-crystal-dependent interaction between the mean solvent electric-field gradient and the solute molecular quadrupole moment. The other contribution is of unknown origin; however, it is essentially identical in all liquid crystals and it can be modeled adequately with a phenomenological mean-field interaction. A remarkable feature of this second interaction is that it causes the average orientation of the asymmetrical isotopomers, and especially of HT, to behave differently from the symmetrical species.},
	keywords = {ELECTRIC-FIELD GRADIENTS, ENVIRONMENTS, LIQUID-CRYSTAL MIXTURES, MECHANISMS, METHANES, MOLECULAR-HYDROGEN, NMR, orientational order, SOLUTES},
	isbn = {1063-651X},
	url = {<Go to ISI>://A1997WD54500062},
	author = {Burnell, E. E. and de Lange, C. A. and Segre, A. L. and Capitani, D. and Angelini, G. and Lilla, G. and Barnhoorn, J. B. S.}
}
@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 {3390,
	title = {High-resolution Fourier transform infrared study of the out-of-plane bending fundamentals of HCOCl and DCOCl},
	journal = {Journal of Molecular Spectroscopy},
	volume = {174},
	number = {2},
	year = {1995},
	note = {ISI Document Delivery No.: TN850Times Cited: 4Cited Reference Count: 32},
	month = {Dec},
	pages = {353-364},
	type = {Article},
	abstract = {High-resolution infrared spectra of the out-of-plane bending (upsilon(6)) fundamentals of the transient molecules HCOCl and DCOCl are reported. The HCOCl band consists of a C-type component due to the out-of-plane transition moment from the ground state and a Coriolis-induced parallel component which derives its intensity from mixing of the 4(1) and 6(1) vibrational states. In DCOCl, the C-type component is absent, so that all of the band intensity comes from Coriolis-induced borrowing from upsilon(4). The DCOCl upsilon(4) and upsilon(6) bands have been fitted simultaneously to account for the strong first-order and weaker second-order a-axis Coriolis interactions between the fundamentals. In HCOCl the upsilon(6) band is only weakly perturbed by upsilon(4) but is more strongly affected by local interactions with the 5(2) vibrational level, which have been explicitly included in the analysis. Ab initio predictions of the relative intensities of the upsilon(6) fundamentals show that the change in dipole moment is much smaller for DCOCl, accounting for the absence of the C-type component. (C) 1995 Academic Press, Inc.},
	keywords = {CH3CL, CL ATOM, FORMYL CHLORIDE, FTIR, GAS-PHASE REACTIONS, KINETICS, MECHANISMS, MICROWAVE-SPECTRUM, OXIDATION},
	isbn = {0022-2852},
	url = {<Go to ISI>://A1995TN85000007},
	author = {Joo, D. L. and Clouthier, D. J. and Merer, A. J.}
}
@article {7259,
	title = {TEMPORAL EMISSION AND ABSORPTION CHARACTERISTICS OF SILVER, LEAD AND MANGANESE IN FURNACE ATOMIZATION PLASMA EXCITATION SPECTROMETRY},
	journal = {Journal of Analytical Atomic Spectrometry},
	volume = {7},
	number = {7},
	year = {1992},
	note = {ISI Document Delivery No.: JY532Times Cited: 15Cited Reference Count: 37},
	month = {Oct},
	pages = {1039-1046},
	type = {Article},
	abstract = {The temporal behaviour of the signal measured for Ag, Pb and Mn in furnace atomization plasma excitation spectrometry was studied using atomic emission and atomic absorption spectrometry. Analyte was deposited both on the wall and on the r.f. electrode with and without the r.f. power applied. Analyte condensation on the r.f. electrode is observed when no plasma is formed. When the plasma is formed inside the furnace it heats the electrode such that, for Ag and Pb, condensation is not observed except for large amounts of analyte. For Ag and Mn, the appearance temperatures and peak temperatures are not significantly affected by the plasma relative to the response obtained using a graphite furnace. For Pb, appearance and peak temperatures are shifted significantly earlier. For Pb, atom formation may be effected by the presence of CO in the gas phase generated from oxidation of the graphite furnace wall and electrode. The role of carbon in atom formation was studied by depositing the sample on both tungsten and graphite electrodes.},
	keywords = {ASCORBIC-ACID, ATOMIC-ABSORPTION, DOUBLE PEAKS, ELECTROTHERMAL ATOMIZATION, FAPES, FURNACE ATOMIZATION PLASMA EXCITATION SPECTROMETRY, GRAPHITE FURNACE, GRAPHITE-FURNACE, LEAD AND MANGANESE SIGNALS, MECHANISMS, silver, SURFACE, TEMPERATURE, vaporization},
	isbn = {0267-9477},
	url = {<Go to ISI>://A1992JY53200002},
	author = {Hettipathirana, T. D. and Blades, M. W.}
}
