Serine dehydratase

Serine dehydratase or L-serine ammonia lyase (SDH) is in the β-family of pyridoxal phosphate-dependent (PLP) enzymes. SDH is found widely in nature, but its structural and chemical properties vary greatly among species. SDH is found in yeast, bacteria, and the cytoplasm of mammalian hepatocytes. The reaction it catalyzes is the deamination of L-serine to yield pyruvate, with the release of ammonia.(See Template:Leucine metabolism in humans – this diagram does not include the pathway for β-leucine synthesis via leucine 2,3-aminomutase) Serine dehydratase or L-serine ammonia lyase (SDH) is in the β-family of pyridoxal phosphate-dependent (PLP) enzymes. SDH is found widely in nature, but its structural and chemical properties vary greatly among species. SDH is found in yeast, bacteria, and the cytoplasm of mammalian hepatocytes. The reaction it catalyzes is the deamination of L-serine to yield pyruvate, with the release of ammonia. This enzyme has 1 substrate, L-serine, and two products, pyruvate and NH3, and uses 1 cofactor, pyridoxal phosphate (PLP). The enzyme's main role is in gluconeogenesis in the liver's cytoplasm. By orienting the substrates and utilizing the PLP coenzyme, SDH lowers the activation energy to convert L-Serine into pyruvate, which can then be converted into glucose. Serine Dehydratase is also known as: HoloEnzyme:The holoenzyme SDH contains 319 residues, 1 PLP cofactor molecule, and 131 water molecules. The overall fold of the monomer is very similar to that of other PLP-dependent enzymes of the Beta-family. The enzyme contains a large domain (catalytic domain or PLP- binding domain) and a small domain. The domains are joined by two peptide linkers (residues 32-35 and 138-146), with the internal gap created being the space for the active site (Figure 1). Figure 1 shows the large catalytic domain in purple and cyan and the small regulatory domain in green in a monomer of Serine Dehydratase. Two monomers(left and right) are shown and the coenzyme PLP is placed in the crevice between the two domains. Two Dimers:Two monomers of hSDS (human SDH) come together to make a dimer. The interface between the two monomers is formed through hydrogen bonds and hydrophobic interactions. The monomer–monomer contacts involve six pairs of hydrogen bonds formed between 10 residues (Arg98-Asn260, Leu310-Asn260, and Leu265-Lys263). Additional interactions include a number of hydrophobic contacts between the residues Met17, Lys21, Asn101, Glu102, Ser306, Ile308, Ser309, and Ile264 in each monomer. (Figure 2). Figure 2 shows the PLP coenzyme situated in the active site of SDH. The purple dashes are the hydrogen bonds involved. Top view of the enzyme.