@article {4578,
	title = {The cellulose-binding domains from Cellulomonas fimi beta-1,4-glucanase CenC bind nitroxide spin-labeled cellooligosaccharides in multiple orientations},
	journal = {Journal of Molecular Biology},
	volume = {287},
	number = {3},
	year = {1999},
	note = {ISI Document Delivery No.: 184RGTimes Cited: 38Cited Reference Count: 46},
	month = {Apr},
	pages = {609-625},
	type = {Article},
	abstract = {The N-terminal cellulose-binding domains CBDN1 and CBDN2 from Cellulomonas fimi cellulase CenC each adopt a jelly-roll beta-sandwich structure with a cleft into which amorphous cellulose and soluble cellooligosaccharides bind. To determine the orientation of the sugar chain within these binding clefts, the association of TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl-4-yl) spin-labeled derivatives of cellotriose and cellotetraose with isolated CBDN1 and CBDN2 was studied using heteronuclear H-1-N-15 NMR spectroscopy. Quantitative binding measurements indicate that the TEMPO moiety does not significantly perturb the affinity of the cellooligo-saccharide derivatives for the CBDs. The paramagnetic enhancements of the amide H-1(N) longitudinal (Delta R-1) and transverse (Delta R-2) relaxation rates were measured by comparing the effects of TEMPO-cellotetraose in its nitroxide (oxidized) and hydroxylamine (reduced) forms on the two CBDs. The bound spin-label affects most significantly the relaxation rates of amides located at both ends of the sugar-binding cleft of each CBD. Similar results are observed with TEMPO-cellotriose bound to CBDN1. This demonstrates that the TEMPO-labeled cellooligosaccharides, and by inference strands of amorphous cellulose, can associate with CBDN1 and CBDN2 in either orientation across their beta-sheet binding clefts. The ratio of the association constants for binding in each of these two orientations is estimated to be within a factor of five to tenfold. This finding is consistent with the approximate symmetry of the hydrogen-bonding groups on both the cellooligosaccharides and the residues forming the binding clefts of the CenC CBDs. (C) 1999 Academic Press.},
	keywords = {CELLULASES, ENDOGLUCANASE, GLYCOSYNTHASE, MAGNETIC-RESONANCE SPECTROSCOPY, NMR, protein-carbohydrate interaction, PROTEINS, SENSITIVITY, SITE, SPECIFICITY, spin label},
	isbn = {0022-2836},
	url = {<Go to ISI>://000079626300013},
	author = {Johnson, P. E. and Brun, E. and Mackenzie, L. F. and Withers, S. G. and McIntosh, L. P.}
}
@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.}
}
