Studies on the complex between human alpha 2-macroglobulin and Crotalus adamanteus proteinase II. Release of active proteinase from the complex.

Proteinase II from Crotalus adamanteus venom formed a complex with human alpha 2-macroglobulin in which approx. 1.7 mol of enzyme were bound per mol inhibitor. The complex did not enzymatically inactivate human alpha 1 proteinase inhibitor. However, active proteinase II was released from the complex in the presence of a high molecular weight proteinase fraction from C. adamanteus venom. The alpha 2-macroglobulin-proteinase II complex was also unstable during incubation in serum, and the enzyme released from the complex caused inactivation of serum proteinase inhibitors. The results indicate conditions under which venom proteinases can be dissociated from their complexes with alpha 2-macroglobulin and thus remain functional in the presence of molar excesses of inhibitor.