title: Dissection of nucleophilic and acid-base catalysis in glycosidases.
abstract: A startling array of added anions have been observed to function as replacement catalytic nucleophiles in mutant glycosidases, including formate, azide, fluoride and other halides. Likewise, the mechanism of acid-base catalysis is somewhat plastic. The carboxylic acids can be substituted by a sulfenic acid or by ascorbate, and the effective acid strength enhanced by the introduction of strong hydrogen bonds. These studies provide an interesting bridge between enzymes and models thereof.
authors.affiliation: Protein Engineering Network of Centres of Excellence of Canada and Department of Chemistry, University of British Columbia, Vancouver, Canada.
authors.forename: D L
authors.initials: DL
authors.lastname: Zechel
authors.forename: S G
authors.initials: SG
authors.lastname: Withers
mesh_terms: D001386:Azides / Q000737:chemistry; D002264:Carboxylic Acids / Q000737:chemistry; D002384:Catalysis; D005459:Fluorides / Q000737:chemistry; D005561:Formates / Q000737:chemistry; D006026:Glycoside Hydrolases / Q000737:chemistry* / Q000378:metabolism; D009113:Muramidase / Q000737:chemistry; D009154:Mutation; D043325:Xylan Endo-1,3-beta-Xylosidase; D014995:Xylosidases / Q000737:chemistry
chemical_list: D001386:Azides; D002264:Carboxylic Acids; D005561:Formates; D006026:Glycoside Hydrolases; D014995:Xylosidases; C022739:thioglucosidase; D009113:Muramidase; D043325:Xylan Endo-1,3-beta-Xylosidase; D005459:Fluorides