ABSTRACT
The proteinases of Trypanosoma cruzi participate in the nutrition of the parasite at the expense of the host, but also appear to be involved in other aspects of the hostparasite relationship. There is evidence that they might be involved in penetration of the trypomastigote into the host cell, since this process is partially sensitive to several well-known proteinase inhibitors (Piras et al., 1985), as well as in evasion from the immune response of the host, either through a ‘fabulation’ mechanism (Krettli et al., 1980) or by intracellular digestion of human IgG endocytosed after binding to specific antigens (Teixeiria and Santana, 1989). In addition, Avila et al., (1979a) have shown that a protein, catalase, is able to satisfy the amino acid requirements of T. cruzi epimastigotes, suggesting that it is taken up by the parasite and degraded by proteinases. Knowledge of the proteinases of the parasite is important for research workers involved in the isolation and purification of antigens and enzymes, so that the enzymes can be inhibited and degradation of the material during preparative procedures prevented.
