Abstract
(1) By sequential chromatography on CM-Sephadex, SP-Sephadex and Sephadex G-100, an esterase-active enzyme was isolated from a commercial preparation of pronase, (2) The purity of the isolated enzyme was proven by disc eleetrophoresis and sedimentation analysis. (3) The molecular weight of the esterase-active enzyme was approximately 16, 000. The sedimentation coefficient was 1.85 S. The N- and C-terminal amino acids were asparagine and valine, respectively. (4) The enzyme was similar to that of bovine trypsin in the substrate specificity. It appeared to be the same as the trypsin-like enzyme isolated from pronase by Wählby (1968) . However, the relative rates of hydrolyses of different substrates by the enzyme differed from those of bovine trypsin. (5) The enzyme activated Clostridium botulinum type E progenitor toxin. Even a higher toxicity was resulted by treating the progenitor toxin with this enzyme than with bovine trypsin. (6) The results support the hypothesis that activation of type E progenitor toxin involves hydrolysis of a lysine ester bond.
