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D-Lactate and related Dehydrogenases, NAD-binding and catalytic domains D-Lactate dehydrogenase (LDH) catalyzes the interconversion of pyruvate and lactate, and is a member of the 2-hydroxyacid dehydrogenase family. LDH is homologous to D-2-Hydroxyisocaproic acid dehydrogenase (D-HicDH) and shares the 2 domain structure of formate dehydrogenase. D-HicDH is a NAD-dependent member of the hydroxycarboxylate dehydrogenase family, and shares the Rossmann fold typical of many NAD binding proteins. D-HicDH from Lactobacillus casei forms a monomer and catalyzes the reaction R-CO-COO(-) + NADH + H+ to R-COH-COO(-) + NAD+. Similar to the structurally distinct L-HicDH, D-HicDH exhibits low side-chain R specificity, accepting a wide range of 2-oxocarboxylic acid side chains. (R)-2-hydroxyglutarate dehydrogenase (HGDH) catalyzes the NAD-dependent reduction of 2-oxoglutarate to (R)-2-hydroxyglutarate. Formate/glycerate and related dehydrogenases of the D-specific 2-hydroxyacid dehydrogenase superfamily include groups such as formate dehydrogenase, glycerate dehydrogenase, L-alanine dehydrogenase, and S-adenosylhomocysteine hydrolase. Despite often low sequence identity, these proteins typically have a characteristic arrangement of 2 similar subdomains of the alpha/beta Rossmann fold NAD+ binding form. The NAD+ binding domain is inserted within the linear sequence of the mostly N-terminal catalytic domain, which has a similar domain structure to the internal NAD binding domain. Structurally, these domains are connected by extended alpha helices and create a cleft in which NAD is bound, primarily to the C-terminal portion of the 2nd (internal) domain. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",