@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 {4020,
	title = {Complete measurement of the pK(a) values of the carboxyl and imidazole groups in Bacillus circulans xylanase},
	journal = {Protein Science},
	volume = {6},
	number = {12},
	year = {1997},
	note = {ISI Document Delivery No.: YK912Times Cited: 44Cited Reference Count: 29},
	month = {Dec},
	pages = {2667-2670},
	type = {Article},
	abstract = {Electrostatic interactions in proteins can be dissected experimentally by determining the pK(a), values of their constituent ionizable amino acids. To complement previous studies of the glutamic acid and histidine residues in Bacillus circulans xylanase (BCX), we have used NMR methods to measure the pK(a)s of the seven aspartic acids and the C-terminus of this protein. The pK(a)s of these carboxyls are all less than the corresponding values observed with random coil polypeptides, indicating that their ionization contributes favorably to the stability of the folded enzyme. In general, the aspartic acids with the most reduced pK(a)s are those with limited exposure to the solvent and a high degree of conservation among homologous xylanases. Most dramatically, Asp 53 and Asp 101 have pK(a)s < 2 and thus remain deprotonated in native BCX under all conditions examined. Asp 83 is completely buried, forming a strong salt bridge with Arg 136. In contrast, Asp 101 is located on the surface of the protein, stabilized in the deprotonated form by an extensive network of hydrogen bonds involving an internal water molecule and the neutral side-chain and main-chain atoms of Ser 100 and Thr 145. These data provide a complete experimental database for theoretical studies of the ionization behavior of BCX under acidic conditions.},
	keywords = {aspartic acid, electrostatics, FAMILIES, NMR, NMR ASSIGNMENTS, NUCLEAR-MAGNETIC-RESONANCE, PK(A), PROTEINS, RESIDUES, SHIFTS, titration, XYLANASE},
	isbn = {0961-8368},
	url = {<Go to ISI>://A1997YK91200024},
	author = {Joshi, M. D. and Hedberg, A. and McIntosh, L. P.}
}
@article {3800,
	title = {Secondary structure and NMR assignments of Bacillus circulans xylanase},
	journal = {Protein Science},
	volume = {5},
	number = {6},
	year = {1996},
	note = {ISI Document Delivery No.: UP617Times Cited: 23Cited Reference Count: 74},
	month = {Jun},
	pages = {1118-1135},
	type = {Article},
	abstract = {Bacillus circulans xylanase (BCX) is a member of the family of low molecular weight endo-beta-(1,4)-xylanases. The main-chain H-1, C-13, and N-15 resonances of this 20.4-kDa enzyme were assigned using heteronuclear NMR experiments recorded on a combination of selectively and uniformly labeled protein samples. Using chemical shift, NOE, J coupling, and amide hydrogen exchange information, 14 beta-strands, arranged in a network of three beta-sheets, and a single cy-helix were identified in BCX. The NMR-derived secondary structure and beta-sheet topology agree closely with that observed in the crystal structure of this protein. The H-N of Ile 118 has a strongly upfield-shifted resonance at 4.03 ppm, indicative of a potential amide-aromatic hydrogen bond to the indole ring of Trp 71. This interaction, which is conserved in all low molecular weight xylanases of known structure, may play an important role in establishing the active site conformation of these enzymes. Following hen egg white and bacteriophage T4 lysozymes, B. circulans xylanase represents the third family of beta-glycanases for which extensive NMR assignments have been reported. These assignments provide the background for detailed studies of the mechanism of carbohydrate recognition and hydrolysis by this bacterial xylanase.},
	keywords = {amide-aromatic hydrogen bond, AMINO-ACID, ASSIGNMENTS, BACKBONE AMIDE, beta-glycanase, C-13-LABELED PROTEINS, C-ALPHA, chemical shift index, CHEMICAL-SHIFTS, COUPLING-CONSTANTS, LARGER PROTEINS, NMR, NUCLEAR-MAGNETIC-RESONANCE, SECONDARY STRUCTURE, SIDE-CHAIN RESONANCES, SOLVENT, SUPPRESSION, XYLANASE},
	isbn = {0961-8368},
	url = {<Go to ISI>://A1996UP61700014},
	author = {Plesniak, L. A. and Wakarchuk, W. W. and McIntosh, L. P.}
}
