Interactions of Bacillus subtilis Alkaline Proteinases with α 2 -Macroglobulin and α 1 -Antitrypsin

Alkaline proteinases of B. subtilis origins bind to α2-macroglobulin and α1-antitrypsin of normal human serum with a resulting inhibition of the proteolytic activities. The interaction of subtilopeptidase A with α2-macroglobulin results in the formation of complexes which, like the complexes formed by trypsin and α2-macroglobulin, are protective insofar as there is a residual proteinase activity which is resistant to inhibition by α1-antitrypsin. The observed interactions are potential determinants of host responses to these proteolytic agents.