An unusual mechanism of glycoside hydrolysis involving redox and elimination steps by a family 4 beta-glycosidase from Thermotoga maritima.
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Yip VL, Varrot A, Davies GJ, Rajan SS, Yang X, Thompson J, Anderson WF, Withers SG
An unusual mechanism of glycoside hydrolysis involving redox and elimination steps by a family 4 beta-glycosidase from Thermotoga maritima.
J Am Chem Soc. 2004 Jul 14;126(27):8354-5.
- PubMed ID
- 15237973 [ View in PubMed]
- Abstract
Among the numerous well-characterized families of glycosidases, family 4 appears to be the anomaly, requiring both catalytic NAD+ and a divalent metal for activity. The unusual cofactor requirement prompted the proposal of a mechanism involving key NAD+-mediated redox steps as well as elimination of the glycosidic oxygen. Primary kinetic isotope effects for the 2- and 3-deutero substrate analogues, isotopic exchange with solvent, and structural analysis of a 6-phospho-beta-glucosidase, BglT (E.C. 3.2.1.6), provided evidence in support of the proposed mechanism, which has striking resemblances to that of the sugar dehydratases. Furthermore, analysis of the stereochemical outcome indicated that family 4 enzymes are retaining glycosidases.