Divergence of substrate specificity within the context of a common structural framework
represents an important mechanism by which new enzyme activity naturally evolves. We
present enzymological and x-ray structural data for hamster chymase-2 (HAM2) that
provides a detailed explanation for the unusual hydrolytic specificity of this rodent α-
chymase. In enzymatic characterization, hamster chymase-1 (HAM1) showed typical
chymase proteolytic activity. In contrast, HAM2 exhibited atypical substrate specificity …