Abstract
The glycoside hydrolase sequence-based classification reveals two families of enzymes which hydrolyse the beta -1,4-linked backbone of xylan, xylanases, termed families GH-10 and GH-11. Family GH-11 xylanases are intriguing in that catalysis is performed via a covalent intermediate adopting an unusual B-2,B-5 (boat) conformation, a conformation which also fulfils the stereochemical constraints of the oxocarbenium ion-like transition state. Here, the 1.9 Angstrom structure of a nucleophile, E94A, mutant of the Xyn11 from Bacillus agaradhaerens in complex with xylotriose is presented. Intriguingly, this complex also adopts the B-2,B-5 conformation in the -1 subsite, with the vacant space provided by the Glu --> Ala mutation allowing the sugar to adopt the alpha -configuration at C1. The structure of the covalent 2-deoxy-2-fluoroxylobiosyl-enzyme intermediate has been extended to atomic (1.1 Angstrom) resolution.
Original language | English |
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Pages (from-to) | 1344-1347 |
Number of pages | 4 |
Journal | Acta Crystallographica. Section D, Biological Crystallography |
Volume | 57 |
Publication status | Published - Sept 2001 |
Keywords
- GLYCOSYL-ENZYME INTERMEDIATE
- CRYSTAL-STRUCTURE
- MACROMOLECULAR STRUCTURES
- XYLANASE
- SPECIFICITY
- REFINEMENT
- CATALYSIS
- SITE