Plasma enzymes that release kinins

Abstract

The present work deals with a further characterization of the kinin liberation process in plasma. Purified plasma kallikrein, plasmin, and kininogenic substrates were prepared from human or equine plasma, and some of their properties were compared. Plasmin and kallikrein were shown to liberate kinins from horse plasma heated for 3 hr at 56°, a kallikreinogen-free substrate; “acid-treated” plasma or purified kininogen was used as substrate only by plasmin. Experiments with these last substrates allowed the conclusion that plasmin by itself has the capacity to release kinins. Hydrolytic actions of kallikrein and plasmin on p- toluene sulfonyl- l-arginine methyl ester (TAMe), benzoyl- l-arginine ethyl ester (BAEE), lysine ethyl ester (LEE), and benzoyl- l-arginine-amide (BAA) showed that plasmin hydrolyzes TAMe, BAEE, and LEE more effectively than does plasma kallikrein. BAA was not hydrolyzed by human or equine plasmin, but it was split by plasma kallikrein. Plasma kallikrein did not hydrolyze casein. A new method of plasma kallikrein purification was developed.