The inactivation of Trypanosoma cruzi proteinases by human α2-macroglobulin (α2-M), a major plasma proteinase inhibitor was studied. Evidences regarding the interaction between α2-M and proteolytic enzymes contained in crude cell-free extracts of T. cruzi were derived from electrophoretic and enzymatic assays. The former showed conformational and structural changes ocurring in α2M, as judged by the appearance of transformed 'fast' form on native PAGE; generation of bands of ~ 90 kDa on reduced SDS-PAGE and formation of covalent complexes enzyme-inhibitor on SDS-PAGE. On the other hand, the total proteolytic activity on azocasein dropped significantly in the presence of α2-M, although partial activity was still maintained. The proteinases detected as a double band of 44 and 53 kDa on gelatin SDS-PAGE were also inhibited by α2M. Results suggest that the study of specific interactions between α2-M and T. cruzi-proteinases, probably with cruzipain, could be biologically important in the fate of T. cruzi-infection and Chagas' disease.
- Alpha 2-macroglobulin
- Trypanosoma cruzi