cellulase and 1-ethyl-3-(4-azonia-4-4-dimethylpentyl)carbodiimide

Differential chemical modification of the cellulase from Schizophyllum commune with [N-methyl-3H]1-ethyl-3(4-azonia-4,4-dimethylpentyl)-carbodiimide in the presence and absence of substrate identified an active site glutamate residue within the peptide: Leu-Gln-Ala-Ala-Thr-Glu-Trp-Leu-(Lys). This Glu residue is proposed to participate in binding of substrate as amino acid sequence homology studies combined with mechanism-based inhibition of the cellulase with 4',5'-epoxypentyl-beta-D-cellobioside identified a neighboring Glu residue, which conforms to the Glu-X-Gly motif of Family 5 glycosidases, as the catalytic nucleophile. These data allow the assignment of the S. commune cellulase to Family 5, subtype 5 of the glycosidases.

Topics: Amino Acid Sequence; Binding Sites; Carbodiimides; Cellulase; Glutamic Acid; Glycoside Hydrolases; Kinetics; Molecular Sequence Data; Peptide Fragments; Schizophyllum; Sequence Alignment; Sequence Homology, Amino Acid