The use of a highly sensitive electrophoretic method to compare the proteinases of trichomonads

Abstract

A highly sensitive electrophoretic method involving gelatin-containing polyacrylamide gels has been used to analyse trichomonad proteinases. Multiple forms, optimally active at pH 5–6, were present in all four species examined, but the species could be distinguished from one another by both quantitative and qualitative differences. The intestinal parasites, Trichomitus batrachorum and Pentatrichomonas hominis, had lower specific activities than the urogenital parasites, Trichomonas vaginalis and Trichomonas foetus, and, in the case of P. hominis, there were fewer enzyme forms. The high activity proteinases of Tritrichomonas foetus had low apparent molecular weights (<25 kDa), while the predominant enzymes of Trichomonas vaginalis were of high apparent molecular weight (68–110 kDa). Distinct differences were also observed between the proteinase patterns of various isolates of T. vaginalis. All of the enzymes were stimulated by dithiothreitol, suggesting that they were cysteine proteinases. This was confirmed for the T. vaginalis and Tritrichomonas foetus proteinases from their inhibition by antipain, leupeptin, TLCK and iodoacetic acid. The method allows the detection of proteinases in samples of Trichomonas vaginalis containing as few as 10 4 cells or as little as 1 μg protein. It was also possible to detect proteinase activity released into the medium. For both T. vaginalis and Tritrichomonas foetus, the extracellular enzymes present during early log phase were qualitatively different from the intracellular proteinases, although the latter were present in samples of media obtained from later cultures (cell densities greater than 1 × 10 5 parasites ml −1). The results show the potential of this technique for detecting proteinases in trichomonad samples in studies aimed at determining proteinase function in pathogenesis and host-parasite relationships.