CHARACTERIZATION OF PROTEINASES IN TRYPANOSOMATIDS

Proteinases are important factors in the pathogenicity of many parasit ic diseases. In this study, the proteolytic activities of 10 trypanoso matids from five different genera (Crithidia, Phytomonas, Endotrypanum , Trypanosoma and Leishmania) were determined by SDS-PAGE containing c opolymerized gelatin as substrate. In almost all species we could dete ct two proteolytic classes, cysteine-and metalloproteinases, based on the inhibition of their activities by E-64 and 1,10-phenanthroline, re spectively. In all cases, the metalloproteinase activities did not cha nge over a broad pH range (from 5.5 to 10). E. schaudinni, T. mega, T. dionisii, C. Iuciliae, C. fasciculata, C. oncopelti and C. guilhermei expressed one or two metalloproteinases of 45-66 kDa, whereas in P. s erpens and P. hyssopifolia a double band of this endopeptidase was det ected at 94 kDa. In contrast, no metalloproteinase activity was observ ed in L. tarentolae. The optimal pH for the cysteine-proteinase activi ties was acidic (about 5.5). In E. schaudinni, T. mega and in Crithidi a 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 Phy tomonas sp., this class of endopeptidase showed a unique feature, in t hat major cysteine-proteinases were found at 29-66 kDa, but multiple, low-activity bands were detected from 116 to 200 kDa. The most strikin g characteristic, however, was the very intense cysteine-proteinase ac tivity expressed by T. dionisii (29-66 kDa). We conclude that these di fferences in the proteolytic profiles could be useful markers to chara cterize and compare trypanosomatids.