Abstract
Methionine synthase, which catalyzes the reaction, 5-methyltetrahydrofolate (5−CH3−H4PteGlu)+homocysteine→methionine+tetrahydrofolate, was detected and partially purified from the human malarial parasite,Plasmodium falciparum (K1 isolate). Partial purification was achieved using high-performance size-exclusion and anion-exchange chromatography. The apparent relative molecular weight of the enzyme was estimated as 105000 daltons, and the apparent Km for 5−CH3−H4PteGlu was 24.2 μM. The enzyme was dependent on adenosylcobalamin or methylcobalamin but not on cobalamin, cyanocobalamin, or hydroxocobalamin in either the absence or presence ofS-adenosylmethionine. Preincubation with nitrous oxide markedly inhibited the enzyme. Methionine synthase inP. falciparum may play a role in the supply of methionine and in folate salvage using exogenous 5−CH3−H4PteGlu for tetrahydrofolate metabolism.
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Krungkrai, J., Webster, H.K. & Yuthavong, Y. Characterization of cobalamin-dependent methionine synthase purified from the human malarial parasite,Plasmodium falciparum . Parasitol Res 75, 512–517 (1989). https://doi.org/10.1007/BF00931158
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DOI: https://doi.org/10.1007/BF00931158