Abstract
When Aspergillus ory, zae IAM 2640 was grown in liquid medium, a high molecular weight acid CPase was produced exclusively in the medium. The enzyme was purified and characterized. The purified enzyme was homogeneous by PAGE at pH 9.4, by isoelectric focusing, and by FPLC, and its molecular weight was 155K by gel filtration. When the 155K enzyme was electrophoresed in SDS-polyacrylamide gel, a single band with a molecular weight of 73K was obtained. The enzyme was inhibited by TPCK and PMSF but not IAA or PCMB. The Km and kcat values of the enzyme for Z-Glu-Tyr, angiotensin, and bradykinin at pH 3.7 and 30°C were 0.48mM, 86 sec-1, 0.1 mM, 0.34sec-1, and 0.06mM, 14.7 sec-1, respectively. The enzyme hydrolyzed proangiotensin and bradykinin sequentially at pH 3.7 from their C-terminus. The enzyme shared an antigen with low molecular weight A. oryzae acid CPase O-1.
