Serine hydroxymethyltransferase
IntroductionIntroduction
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FunctionFunction
Serine hydroxymethyltransferase (SHMT) is part of the pyridoxal phosphate (PLP)-dependent enzymes. Specifically, the enzyme belongs to the alpha-class. This enzyme is utilized mainly for two functions. First, the enzyme catalyzes the reversible conversion of serine to glycine. Chemically speaking, the enzyme performs a retro-aldol cleavage. Second, the enzyme catalyzes the reversible conversion of tetrahydrofolate to 5,10-methylene tetrahydrofolate. There appear to be multiple isoforms of the enzyme in bacteria. Serine hydroxymethyltransferase isoforms have namely been identified from Escherichia coli and Bacillus stearothermophilus. In mammals, there are two separate isoforms of SHMT in the cytoplasm and the mitochondria. In plants, there is an additional SHMT isoform found within the chloroplast. The diverse presence of serine hydroxymethyltransferase is in part because of the importance of 5,10-methylene tetrahydrofolate. This intermediate is important for the synthesis of the essential biomolecules purine, thymidine, choline, and methionine. The enzyme monomer fold is comprised of the c-terminal domain and the N-Terminal Domain. The C-terminal domain folds into an αβ sandwich. The N-terminal domain is comprised of two further domains. The first N-terminal sub-domain is a smaller domain composed of only 3 α-helices and 1 β-strand. The second N-terminal subdomain is the PLP binding domain. This sub-domain folds into an αβα structure that has a seven-stranded mixed β sheet surrounded by α-helices on both sides, hence αβα. This enzyme has important implications in disease
StructureStructure
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