Cell-associated and extracellular proteolytic activity of an oral flagellate, Trichomonas tenax

Proteolytic activities in crude extracts and culture filtrates from Trichomonas tenax were determined using hide powder azure as substrate and the proteinase profiles in both samples were analysed in SDS-polyacrylamide gels containing copolymerized gelatin. The enzyme activity in the crude extract was detected over a broad pH range and was strongly activated by dithiothreitol, mainly in the pH range 5–8, and inhibited by cysteine proteinase inhibitors. Extracellular enzyme activity in culture filtrates was SH-dependent and increased continuously during incubation of the cell suspension, suggesting proteinase release. A total of seven distinct proteolytic bands could be detected in crude preparations. Three of these, with apparent M r values 35,000, 45,000 and 56,000 and a pH optimum of 4–7, were SH-dependent and their inhibitory sensitivities were characteristic for cysteine proteinases. The 45,000 and 56,000 proteinases probably corresponded to those found in the culture filtrates. Proteolytic bands with apparent M r 76,000, 87,000, 102,000 and 270,000 and pH optima in the alkaline region, pH 8–9, were independent of SH groups and were inhibited by a chelating agent EDTA, suggesting that they belong to the metalloproteinase family.