1nh6
From Proteopedia
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'''Structure of S. marcescens chitinase A, E315L, complex with hexasaccharide''' | '''Structure of S. marcescens chitinase A, E315L, complex with hexasaccharide''' | ||
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[[Category: Roey, P Van.]] | [[Category: Roey, P Van.]] | ||
[[Category: Worth, C.]] | [[Category: Worth, C.]] | ||
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Revision as of 23:31, 2 May 2008
Structure of S. marcescens chitinase A, E315L, complex with hexasaccharide
Overview
The sizes and anomers of the products formed during the hydrolysis of chitin oligosaccharides by the Family 18 chitinase A (ChiA) from Serratia marcescens were analysed by hydrophilic interaction chromatography using a novel approach in which reactions were performed at 0 degrees C to stabilize the anomer conformations of the initial products. Crystallographic studies of the enzyme, having the structure of the complex of the ChiA E315L (Glu315-->Leu) mutant with a hexasaccharide, show that the oligosaccharide occupies subsites -4 to +2 in the substrate-binding cleft, consistent with the processing of beta-chitin by the release of disaccharide at the reducing end. Products of the hydrolysis of hexa- and penta-saccharides by wild-type ChiA, as well as by two mutants of the residues Trp275 and Phe396 important in binding the substrate at the +1 and +2 sites, show that the substrates only occupy sites -2 to +2 and that additional N -acetyl-D-glucosamines extend beyond the substrate-binding cleft at the reducing end. The subsites -3 and -4 are not used in this four-site binding mode. The explanation for these results is found in the high importance of individual binding sites for the processing of short oligosaccharides compared with the cumulative recognition and processive hydrolysis mechanism used to digest natural beta-chitin.
About this Structure
1NH6 is a Single protein structure of sequence from Serratia marcescens. Full crystallographic information is available from OCA.
Reference
Family 18 chitinase-oligosaccharide substrate interaction: subsite preference and anomer selectivity of Serratia marcescens chitinase A., Aronson NN Jr, Halloran BA, Alexyev MF, Amable L, Madura JD, Pasupulati L, Worth C, Van Roey P, Biochem J. 2003 Nov 15;376(Pt 1):87-95. PMID:12932195 Page seeded by OCA on Sat May 3 02:31:29 2008
