Characterization of proteinases in trypanosomatids

Proteinases are important factors in the pathogenicity of many parasitic diseases. In this study, the proteolytic activities of 10 trypanosomatids from five different genera (Crithidia, Phytomonas, Endotrypanum, Trypanosoma and Leishmania) were determined by SDS-PAGE containing copolymerized gelatin as substrate. In almost all species we could detect two proteolytic classes, cysteine- and metalloproteinases, based on the inhibition of their activities by E-64 and 1,10-phenanthroline, respectively. In all cases, the metalloproteinase activities did not change over a broad pH range (from 5.5 to 10). E. schaudinni, T. mega, T. dionisii, C. luciliae, C. fasciculata, C. oncopelti and C. guilhermei expressed one or two metalloproteinases of 45-66 kDa, whereas in P. serpens and P. hyssopifolia a double band of this endopeptidase was detected at 94 kDa. In contrast, no metalloproteinase activity was observed in L. tarentolae. The optimal pH for the cysteine-proteinase activities was acidic (about 5.5). In E. schaudinni, T. mega and in Crithidia sp., these proteinases had an apparent molecular weight of 66-94 kDa, while L. tarentolae expressed a broad band from 29 to 45 kDa. In Phytomonas sp., this class of endopeptidase showed a unique feature, in that major cysteine-proteinases were found at 29-66 kDa, but multiple, low-activity bands were detected from 116 to 200 kDa. The most striking characteristic, however, was the very intense cysteine-proteinase activity expressed by T. dionisii (29-66 kDa). We conclude that these differences in the proteolytic profiles could be useful markers to characterize and compare trypanosomatids.