Inactivation of human plasma alpha 1-proteinase inhibitor by human PMN leucocyte collagenase.

Highly purified human polymorphonuclear leucocyte collagenase cleaved human alpha-1-proteinase inhibitor (alpha 1-PI) at the carboxyl site of Phe352 (P7). The inhibitor was thereby rapidly inactivated and generated a primary degradation product as shown by reverse-phase HPLC and N-terminal sequencing. Prolonged incubation of the modified inhibitor with polymorphonuclear leucocyte collagenase led to the generation of a secondary degradation product with additional cleavage at the carboxyl site of Pro357 (P2).