Inactivation of human plasma alpha 1-proteinase inhibitor by a metalloproteinase from Serratia marcescens.

The interaction of a Serratia marcescens metalloproteinase with human plasma alpha 1-proteinase inhibitor has been investigated. The enzyme was not inactivated by this inhibitor but, instead, converted the native plasma protein into an inactive form of decreased molecular weight. Amino terminal sequence analysis indicated that the interaction of the inhibitor and enzyme was at the reactive site of the inhibitor, with peptide-bond cleavage resulting in the inactivation. This process may be important in necrotic processes occurring during bacterial infiltration of host tissues.