Somchart MaenpuenKittipat SopitthummakhunYongyuth YuthavongPimchai ChaiyenUbolsree LeartsakulpanichMahidol UniversityThailand National Center for Genetic Engineering and Biotechnology2018-09-132018-09-132009-11-01Molecular and Biochemical Parasitology. Vol.168, No.1 (2009), 63-73016668512-s2.0-68949187841https://repository.li.mahidol.ac.th/handle/123456789/27125Serine hydroxymethyltransferase (SHMT) is a ubiquitous enzyme required for folate recycling and dTMP synthesis. A cDNA encoding Plasmodium falciparum (Pf) SHMT was expressed as a hexa-histidine tagged protein in Escherichia coli BL21-CodonPlus®(DE3)-RIL. The protein was purified and the process yielded 3.6 mg protein/l cell culture. Recombinant His6-tagged PfSHMT exhibits a visible spectrum characteristic of pyridoxal-5′-phosphate enzyme and catalyzes the reversible conversion of l-serine and tetrahydrofolate (H4folate) to glycine and 5,10-methylenetetrahydrofolate (CH2-H4folate). Steady-state kinetics study indicates that His6-tagged PfSHMT catalyzes the reaction by a ternary-complex mechanism. The sequence of substrate binding to the enzyme was also examined by glycine product inhibition. A striking property that is unique for His6-tagged PfSHMT is the ability to use d-serine as a substrate in the folate-dependent serine-glycine conversion. Kinetic data in combination with expression result support the proposal of SHMT reaction being a regulatory step for dTMP cycle. This finding suggests that PfSHMT can be a potential target for antimalarial chemotherapy. © 2009 Elsevier B.V.Mahidol UniversityBiochemistry, Genetics and Molecular BiologyImmunology and MicrobiologyArticleSCOPUS10.1016/j.molbiopara.2009.06.010