Digestion of the basic trypsin inhibitor of bovine pancreas by thermolysin

Extensive digestion of the basic trypsin inhibitor by thermolysin at 60–80° has been demonstrated by loss of inhibitory activity, increase in ninhydrin positive material and separation of the breakdown products by electrophoresis. Formation of the inhibitor-trypsin complex does not protect the inhibitor from digestion by thermolysin; both components are digested. Between 40° and 80° the inhibitor undergoes a reversible transition involving a slight conformational change; this may account for its susceptibility to thermolysin.