AMINOPEPTIDASES FROM PLASMODIUM-FALCIPARUM, PLASMODIUM-CHABAUDI CHABAUDI AND PLASMODIUM-BERGHEI

Using fluorogenic substrates and polyacrylamide gels we detected in ce ll-free extracts of Plasmodium falciparum, Plasmodium chabaudi chabaud i and Plasmodium berghei only a single aminopeptidase. A comparative s tudy of the aminopeptidase activity in each extract revealed that the enzymes have similar specificities and kinetics, a near-neutral pH opt ima of 7.2 and are moderately thermophilic. Each has an apparent molec ular weight of 80,000 +/- 10,000, determined by high performance liqui d chromatography on a calibrated SW500 column. Whilst the P. c. chabau di and P. berghei activity co-migrate in native polyacrylamide gels, t hat of P. falciparum migrates more slowly. The three enzymes can be se lectively inhibited by ortho-phenanthroline and are thus metalloaminop eptidases; however, in contrast to other aminopeptidases the metal co- factor does not appear to be Zn2+.