Serine hydroxymethyltransferase from Plasmodium vivax is different in substrate specificity from its homologues.

摘要: The putative gene of Plasmodium vivax serine hydroxymethyltransferase (PvSHMT; EC 2.1.2.1) was cloned and expressed in Escherichia coli. purified enzyme shown to be a dimeric protein with monomeric molecular mass 49 kDa. PvSHMT has maximum absorption peak at 422 nm molar coefficient 6370 m−1·cm−1. Kd for binding the pyridoxal-5-phosphate 0.14 ± 0.01 μm. An alternative assay measuring tetrahydrofolate-dependent SHMT activity based on coupled reaction 5,10-methylenetetrahydrofolate reductase (EC 1.5.1.20) from E. coli developed. uses ternary-complex mechanism kcat value 0.98 ± 0.06 s−1 Km values 0.18 ± 0.03 0.14 ± 0.02  mm l-serine tetrahydrofolate, respectively. optimum pH 8.0 an Arrhenius’s plot showed transition temperature 19 °C. Besides l-serine, forms external aldimine complex d-serine, l-alanine, l-threonine glycine. also catalyzes tetrahydrofolate-independent retro-aldol cleavage 3-hydroxy amino acids. Although is physiological substrate reaction, can use d-serine. In absence tetrahydrofolate high pH, enzyme–quinonoid but not whereas rabbit liver reported form l-serine. specificity difference between mammalian indicates dissimilarity their active sites, which could exploited development specific inhibitors against PvSHMT.