AGRO 175 |
| β-D-Xylosidase from Selenomonas ruminantium has been revealed as the best catalyst known for promoting hydrolysis of 1,4-β-D-xylooligosaccharides and it has potential utility in saccharification processes. Kinetic parameters, kcat and kcat/Km, are more than 10-fold larger than those reported for the enzyme isolated from other organisms. In cleaving 1,4-glycosidic bonds, the family 43 glycoside hydrolase acts through an inversion mechanism, and cleaves a single xylose residue from the nonreducing end of xylooligosaccharides per catalytic cycle without processivity. Three-dimensional structures of homologous GH43 xylosidases indicate that the enzyme active site has only two subsites for recognition of substrate, the two terminal xylosyl residues that share the sessile glycosidic bond. The pKa values of the catalytic acid (ca. 7) and catalytic base (ca. 5) and the two subsites of the active site are key components of a kinetic model that accounts for catalytic properties such as substrate specificities, inhibitor binding, and influences of pH. |
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Agricultural Biomass, Biobased Products, and Biofuels
1:30 PM-5:10 PM, Wednesday, March 28, 2007 McCormick Place South -- Room S103D, Level 1, Oral
Division of Agrochemicals |