Serine hydroxymethyltransferase (SHMT) fromBacillus stearothermophilus (bsSHMT) is a pyridoxal 5¢-phosphate-dependent enzyme that catalyses the conversion of l-serine and tetrahydrofolate to glycine and 5,10-methylene tetrahydrofolate. In addition, the enzyme catalyses the tetrahydrofolate-independent cleavage of 3-hydroxy amino acids and transamination.