Isolation and structure of a tryptic glycopeptide from the active site of beta-glucosidase A3 from Aspergillus wentii.

A radioactive glycopeptide with a molecular weight of 13 200 was isolated from beta-glucosidase A3 after labeling the active site with [3H]conduritol B epoxide and cleavage with trypsin. The glycopeptide consists of 63 amino acids and 29 +/- 1 sugar residues. Its amino acid sequence was derived from the results of sequence analysis of peptic and cyanogen bromide peptides. The radioactive inhibitor is bound to aspartic acid 12 of the sequence, the sugar residues are probably bound as N-glycosides to asparagine 48 and asparagine 56, since O-glycosidic linkages have been ruled out.