Crystal structures of the laminarinase catalytic domain from Thermotoga maritima MSB8 in complex with inhibitors: essential residues for β-1,3- and β-1,4-glucan selection.

ABSTRACT: Laminarinases hydrolyzing the β-1,3-linkage of glucans play essential roles in microbial saccharide degradation. Here we report the crystal structures at 1.65-1.82 Å resolution of the catalytic domain of laminarinase from the thermophile Thermotoga maritima with various space groups in the ligand-free form or in the presence of inhibitors gluconolactone and cetyltrimethylammonium. Ligands were bound at the cleft of the active site near an enclosure formed by Trp-232 and a flexible GASIG loop. A closed configuration at the active site cleft was observed in some molecules. The loop flexibility in the enzyme may contribute to the regulation of endo- or exo-activity of the enzyme and a preference to release laminaritrioses in long chain carbohydrate hydrolysis. Glu-137 and Glu-132 are proposed

SUBMITTER: Jeng WY 

PROVIDER: S-EPMC3247943 | biostudies-literature | 2011 Dec

REPOSITORIES: biostudies-literature