A classification of glycosyl hydrolases based on amino acid sequence similarities

TLDR

The study discusses how the classification informs enzyme folding, catalytic mechanisms, and the evolution of carbohydrate metabolism. The authors compared amino‑acid sequences of 301 glycosyl hydrolases and related enzymes. Of 301 sequences, 291 (39 EC entries) were assigned to 35 families, leaving 10 unclassified, while 18 families were monospecific and 17 polyspecific, suggesting the classification system may need revision as data grow.

Abstract

The amino acid sequences of 301 glycosyl hydrolases and related enzymes have been compared. A total of 291 sequences corresponding to 39 EC entries could be classified into 35 families. Only ten sequences (less than 5% of the sample) could not be assigned to any family. With the sequences available for this analysis, 18 families were found to be monospecific (containing only one EC number) and 17 were found to be polyspecific (containing at least two EC numbers). Implications on the folding characteristics and mechanism of action of these enzymes and on the evolution of carbohydrate metabolism are discussed. With the steady increase in sequence and structural data, it is suggested that the enzyme classification system should perhaps be revised.