Plasmodium berghei: a study of globinolytic enzyme in erythrocytic parasite

An acid protease of Plasmodium berghei (NK 65) was extracted from parasite lysate and purified by means of gel filtration followed by DEAE-sephadex column chromatography. The enzyme showed especially high activity to degrade hemoglobin. The pH optimum of the purified enzyme was 3.2, Km value was 0.012 mM. Molecular weight of the enzyme was estimated by gel chromatography as being 18,000-20,000. The enzyme activity was specifically inhibited by pepstatin, one of the peptide aldehyde protease inhibitors. These features of the enzyme were similar to those of acid protease taken from Dirofilaria immitis which also metabolizes hemoglobin as the major nutrient source.