Interactions of <i>Bacillus subtilis</i> Alkaline Proteinases with α<sub>2</sub>-Macroglobulin and α<sub>1</sub>-Antitrypsin

Abstract

Alkaline proteinases of <i>B. subtilis </i>origins bind to α<sub>2</sub>-macroglobulin and α<sub>1</sub>-antitrypsin of normal human serum with a resulting inhibition of the proteolytic activities. The interaction of subtilopeptidase A with α<sub>2</sub>-macroglobulin results in the formation of complexes which, like the complexes formed by trypsin and α<sub>2</sub>-macroglobulin, are protective insofar as there is a residual proteinase activity which is resistant to inhibition by α<sub>1</sub>-antitrypsin. The observed interactions are potential determinants of host responses to these proteolytic agents.