Plasmodium knowlesi: in vitro Biosynthesis of Methionine and Thymidylic Acid.

摘要

Methionine and thymidylic acid biosynthesis were studied to investigate methyl group sources in rhesus monkey erythrocytes infected with Plasmodium knowlesi malaria which were cultured in vitro with radioisotopically labeled serine, histidine, formaldehyde, choline, betaine, sarcosine, and 5-formyltetrahydrofolic acid. Thin layer chromatography of acid hydrolysates of washed erythrocytes showed that only serine was utilized as a methyl donor. In studies utilizing labeled serine and homocysteine, the results obtained with pyrimethamine and 5-fluoro-orotic acid were consistent with their modes of action. Large increased in thymidylic acid synthesis occurred after addition of para-aminobenzoic, dihydrofolic and tetrahydrofolic acids, and smaller increases after addition of folic and diglutamyl folic acids to cultures containing labeled serine. (Author)