Interactions in Vitro and in Vivo between Dog Trypsin and Dog Plasma Protease Inhibitors

Abstract

Trace amounts of dog trypsin mixed with dog serum or injected i.v. into the dog were bound mainly to the a-macroglobulins (82 per cent) and to α₁-antitrypsin (18 per cent). The relative affinity of dog trypsin for the α-macroglobulins was about 30 times as high as for the other inhibitors taken together. Dog trypsin bound to α₁-antitrypsin was rapidly taken over by the α-macroglobulins in vitro as well as in vivo. The trypsin-α-macroglobulin complexes injected i.v. or formed in vivo were rapidly eliminated from the blood stream following a first order reaction, while α₁-antitrypsin-bound trypsin disappeared much slower as found for bovine trypsin and dog plasma trypsin inhibitors.

Key Words:

• α-globulins
• macroglobulins
• trypsin
• trypsin inhibitors