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Dissection of nucleophilic and acid–base catalysis in glycosidases

2001; Elsevier BV; Volume: 5; Issue: 6 Linguagem: Inglês

10.1016/s1367-5931(01)00260-5

1879-0402

David L. Zechel, Stephen G. Withers,

Amino Acid Enzymes and Metabolism

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.