@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 {4314,
	title = {Equilibrium unfolding of proteins monitored by electrospray ionization mass spectrometry: Distinguishing two-state from multi-state transitions},
	journal = {Rapid Communications in Mass Spectrometry},
	volume = {12},
	number = {8},
	year = {1998},
	note = {ISI Document Delivery No.: ZJ143Times Cited: 79Cited Reference Count: 59},
	pages = {435-442},
	type = {Article},
	abstract = {The acetic acid-induced unfolding of cytochrome c (cyt c) and apomyoglobin (aMb) are studied under equilibrium conditions by electrospray ionization (ESI) mass spectrometry (MS), The folding states of the proteins in solution are monitored by the charge state distributions that they produce during ESI, A tightly folded protein shows lower charge states than the same protein in an unfolded conformation. The ESI-MS data presented in this study show that during the denaturation of cyt c, only two distinct charge state distributions are observed. These can be attributed to the native and to the acid-unfolded conformation, respectively. In the transition region where the folded and the unfolded conformation are both present in solution, these two distributions are observed simultaneously, thus giving rise to a bimodal ESI mass spectrum. These data reflect a highly cooperative (two state) folding behavior. In contrast, the acid-induced unfolding of aMb is accompanied by gradual shifts in the maxima of the observed charge state distribution. This indicates a non cooperative unfolding behavior involving multiple protein conformations. The observations made here suggest that ESI-MS might be a general method for assessing the cooperativity of protein unfolding transitions. This study also addresses the issue of {\textquoteright}secondary{\textquoteright} solvent effects for ESI-MS studies on the acid-induced unfolding of proteins. These effects influence the ESI charge state distribution without being related to conformational changes of the protein in solution and could potentially complicate the interpretation of ESI mass spectra, Data obtained for bovine pancreatic trypsin inhibitor and ubiquitin indicate that secondary solvent effects influence the observed charge state distributions only to a very minor extent between pH 8.5 and 2.5. (C) 1998 John Wiley \& Sons, Ltd.},
	keywords = {CONFORMATIONAL-CHANGES, CYTOCHROME-C, FERRICYTOCHROME-C, FOLDING, HYDROGEN-DEUTERIUM EXCHANGE, INTERMEDIATE, MOLECULAR-BASIS, MOLTEN GLOBULE, NMR-SPECTROSCOPY, POSITIVE-ION, STRUCTURAL CHARACTERIZATION},
	isbn = {0951-4198},
	url = {<Go to ISI>://000073183800005},
	author = {Konermann, L. and Douglas, D. J.}
}
@article {3936,
	title = {An extended mass range quadrupole for electrospray mass spectrometry},
	journal = {International Journal of Mass Spectrometry and Ion Processes},
	volume = {162},
	number = {1-3},
	year = {1997},
	note = {ISI Document Delivery No.: XD007Times Cited: 10Cited Reference Count: 39},
	month = {Mar},
	pages = {121-127},
	type = {Article},
	abstract = {The mass range of a quadrupole mass spectrometer with an electrospray source has been increased from m/z 4000 to m/z 8585 by lowering the radio frequency of the quadrupole power supply from 1.00 MHz to 683 kHz. Unit mass resolution at m/z 5030 can be achieved. The sensitivity below m/z 3000 shows only small changes as expected from phase space arguments. Spectra of poly propylene glycol and soybean agglutinin with peaks in the range m/z 4000-7000 are described. (C) 1997 Elsevier Science B.V.},
	keywords = {CLUSTERS, COMPLEXES, CONFORMATIONAL-CHANGES, DISSOCIATION, ELECTROSPRAY, high mass, IONIZATION-POTENTIALS, IONS, non-covalent, NONCOVALENT INTERACTIONS, PROTEINS, quadrupole mass spectrometer, SOYBEAN AGGLUTININ},
	isbn = {0168-1176},
	url = {<Go to ISI>://A1997XD00700011},
	author = {Collings, B. A. and Douglas, D. J.}
}
