(R)-2-Hydroxyglutarate Dehydrogenase and related dehydrogenases, NAD-binding and catalytic domains
(R)-2-hydroxyglutarate dehydrogenase (HGDH) catalyzes the NAD-dependent reduction of 2-oxoglutarate to (R)-2-hydroxyglutarate. HGDH is a member of the D-2-hydroxyacid NAD(+)-dependent dehydrogenase family; 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.