Substrate specificity of carboxyl proteinase fromPycnoporus coccineus, a wood-deteriorating fungus

A carboxyl proteinase was purified from submerged-culture filtrate of a wood-deteriorating basidiomycete,Pycnoporus coccineus. The purified enzyme was found to be essentially homogeneous in disc gel electrophoresis tests at pH 9.4 and 2.3. The specificity and mode of action ofP. coccineus carboxyl proteinase Ia were investigated with the oxidized B-chain of insulinP. coccineus carboxyl proteinase Ia hydrolyzed primarily three peptide bonds, Ala14-Leu15, Tyr16-Leu17, and Phe24-Phe25 bonds, in the oxidized B-chain of insulin.