Inactivation of human plasma α1‐proteinase inhibitor by human PMN leucocyte collagenase

Abstract
Highly purified human polymorphonuelear leucocyte collagenase cleaved human α‐1‐proteinase inhibitor (α1‐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).