IN-VITRO EFFECT OF PROTEASES ON HUMAN AND RAT PLASMA ALPHA-MACROGLOBULIN ACTIVITY

Human plasma alpha(2)- macroglobulin activity decreased upon incubatio n for 12 hours at 37 degrees C in the presence of aminopeptidase (5 mu g/0.1 ml), while the immunoreactivity of the inhibitor did not signif icantly alter under the same conditions. This observation indicates th at the inhibitor protein was not extensively degraded on treatment wit h aminopeptidase. Inactivation of alpha(2) - macroglobulin by aminopep tidase was found to be a pH and temperature dependent process. While S treptomyces caesiptosus protease (5 mu g/0.05 ml) inactivated patially purified human plasma alpha(2)-macroglobulin within fifteen minutes o f incubation at 37 degrees C, the action of Streptomyces griseus (15 m u g), pronase (15 mu g) and aminopeptidase (5 mu g) appeared to be tim e dependent. The alpha-macroglobulin activity in ten fold diluted rat plasma was completely abolished in the presence of Bacillus amyloliqui faciens protease (15 mu g) whereas, moderate inactivation was observed in the presence of Streptomyces griseus protease (15 mu g) and Strept omyces caesiptosus protease (15 mu g) upon incubation at 37 degrees C for 12 hours.