title: Determination of the catalytic base in family 48 glycosyl hydrolases.
abstract: The catalytic base in family 48 glycosyl hydrolases has not been previously established experimentally. Based on structural and modeling data published to date, we used site-directed mutagenesis and azide rescue activity assays to show definitively that the catalytic base in Thermobifida fusca Cel48A is aspartic acid 225. Of the tested mutants, only Cel48A with the D225E mutation retained partial activity on soluble and insoluble substrates. In azide rescue experiments, only the D225G mutation, in the smallest residue tested, showed an increase in activity with added azide.
authors.affiliation: Department of Molecular Biology and Genetics, Cornell University, 458 Biotechnology Building, Ithaca, NY 14853, USA.
authors.forename: Maxim
authors.initials: M
authors.lastname: Kostylev
authors.forename: David B
authors.initials: DB
authors.lastname: Wilson
mesh_terms: D000192:Actinomycetales / Q000201:enzymology* / Q000378:metabolism*; D019943:Amino Acid Substitution / Q000235:genetics; D020134:Catalytic Domain; D006026:Glycoside Hydrolases / Q000235:genetics* / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D050505:Mutant Proteins; D006026:Glycoside Hydrolases