Studies on the inhibition of proteolytic enzymes by serum. II. Demonstration that separate proteolytic inhibitors exist in serum; their distinctive properties and the specificity of their action.

Increases in serum proteolytic inhibition with disease were found to be specific either for plasmin or for trypsin and chymotrypsin. In normal serum, the plasmin inhibitor could be differentiated from the trypsin and chymotrypsin inhibitor by various physical and chemical means. There was no apparent difference between the trypsin inhibitor and the chymotrypsin inhibitor in serum. No qualitative differences were found between the inhibitors of normal sera and the inhibitors of sera showing elevated inhibition.