Purification and Some Properties of Dipeptidyl Carboxypeptidase from Bacillus pumilus

An intracellular protease from a bacterium, Bacillus pumilus HL721, was purified about 5000-fold by Chromatography with a Q-Sepharose Fast Flow column, TSK-gel HA-1000 glass column, and TSK-gel G3000SWXL column using Bz-Gly-Ala-Pro as a substrate. The enzyme was the most active at pH around 7.5 and stable from 4.5 and 8.0. The enzyme activity was inhibited by Cu²⁺, EDTA, N-ethylmaleimide, o-phenanthroline, and p-chloromercuribenzoic acid. The molecular weight of the enzyme was 155,000 by gel filtration. The enzyme removed dipeptide from the carboxyl end of some peptides used as substrates. From these results the enzyme seems to be a dipeptidyl carboxypeptidase.