[Protaminase activity of plasma. III. Role of conversion enzyme (kininase II) in protaminase activity of plasma].

Kininase I (carboxypeptidase N) and kininase II (angiotensin converting enzyme) were isolated from human plasma by gel filtration on Sephadex G 200, then separated and partially purified by ion exchange chromatography. These two partially purified enzymic preparations allowed us to demonstrate that protamine underwent an extensive degradation only when both kininases acted simultaneously. The effects of CoCl2, an activator, and of several inhibitors, amongst which captopril, suggest that the same enzymatic system is responsible for the in vitro protaminasic activity of diluted unfractionated plasma.