CATHEPSIN B-LIKE CYSTEINE PROTEASES OF LEISHMANIA-MEXICANA

A group of Leishmania mexicana cysteine proteases that differ from tho se previously found in this protozoon are described. The enzymes chara cteristically have a preference for peptidyl substrates with a phenyla lanyl-valyl-arginyl moiety, do not hydrolyse gelatin in substrate-sodi um dodecyl sulphate polyacrylamide gels, are stimulated by thiol-reduc ing agents and are sensitive to inhibitors specific for cysteine prote ases. They have unusual solubility properties that indicate that the e nzymes are amphiphilic proteins. Two of the cysteine proteases have be en purified from L. mexicana amastigotes and shown to have molecular m asses of 31 and 33 kDa. Their N-terminal amino acid sequences are very similar and show high homology to the mammalian cysteine protease, ca thepsin B.