ABSTRACT
The study of proteinases in African trypanosomes, is still in its infancy. The only well-defined class of proteinase identified so far is the cysteine proteinase group (North et al., 1983; Lonsdale-Eccles and Mpimbaza, 1986). There has also been a report of acid (or aspartic) proteinases in African trypanosomes (Venkatesan et al., 1977), but this has not been substantiated. It is likely that the latter activity was a lysosomal cysteine proteinase rather than a cathepsin D-like aspartic enzyme. Nevertheless, the lack of demonstrable aspartic proteinase activity should not be considered as proof of the absence of such enzymes. It should be remembered that the aspartic and cysteine proteinases of the lysosomes of mammalian cells act in concert.
