Endopeptidases fromPlasmodium knowlesi

Abstract

SummaryExtracts of rhesus monkey erythrocytes infected withPlasmodium knowlesiwere fractionated by polyacrylamide gel electrophoresis (PAGE) and several zones of endopeptidase activity were demonstrated by an imprint-digest method. The enzymes were active only under acid conditions; activity was detected at pH 3·2 but not between pH 6·4 and 8·9 using haemoglobin, albumin or erythrocyte lysate as the substrate. Optimized PAGE conditions separated highly active parasite enzymes withRfvalues of 73, 63 and 53 (± 7%), as well as a red cell endopeptidase,Rf44. Of two other minor bands of activity, one was associated with platelets.