Electrophoretic detection of Trypanosoma cruzi peptidases

Peptidases of Trypanosoma cruzi epimastigotes were examined by polyacrylamide gel electrophoresis in gels containing gelatin as peptidase substrate. Mini-gels were far superior to large gels in their sensitivity of peptidase detection. Patterns of peptidases were similar between different strains of T. cruzi, although some inter-strain heterogeneity was found. In strain Y, at least five peptidases were detected: four of these enzymes were shown to be cysteine-type peptidases with acidic pH optima. The other peptidase was a 60-kDa membrane-associated peptidase that was sensitive to o-phenanthroline; it was tentatively characterised as a metallopeptidase, and was optimally active at alkaline pH. This membrane-associated peptidase was conserved between strains of T. cruzi.