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Hydroxyacid-oxoacid transhydrogenase (HOT) involved in gamma-hydroxybutyrate metabolism This family contains hydroxyacid-oxoacid transhydrogenase (HOT), also known as D-2-hydroxyglutarate transhydrogenase. It catalyzes the conversion of gamma-hydroxybutyrate (GHB) to succinic semialdehyde (SSA), coupled to the stoichiometric conversion of alpha-ketoglutarate to D-2-hydroxyglutarate in gamma-Hydroxybutyrate catabolism. Unlike many other alcohols, which are oxidized by NAD-linked dehydrogenases, gamma-hydroxybutyrate is metabolized to succinate semialdehyde by hydroxyacid-oxoacid transhydrogenase which does not require free NAD or NADP; instead, it uses alpha-ketoglutarate as an acceptor, converting it to d-2-hydroxyglutarate. Alpha-ketoglutarate serves as an intermediate acceptor to regenerate NAD(P) required for the oxidation of GHB. HOT also catalyzes the reversible oxidation of a hydroxyacid obligatorily coupled to the reduction of an oxoacid, and requires no cofactor. In mammals, the HOT enzyme is located in mitochondria, and is expressed with an N-terminal mitochondrial targeting sequence. HOT enzyme is member of the metal-containing alcohol dehydrogenase family. It typically contains an iron although other metal ions may be used. |
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