SDH N-terminal domain is named due to its appearance at the N-terminal of SDH in eukaryotes, but can be found C-terminal of the SDH-like domain in other enzymes, such as the bifunctional lysine ketoglutarate reductase/saccharopine dehydrogenase enzyme. SDH catalyzes the final step in the reversible NAD-dependent oxidative deamination of saccharopine to alpha-ketoglutarate and lysine, in the alpha-aminoadipate pathway of L-lysine biosynthesis. SHD is structurally related to formate dehydrogenase and similar enzymes, having a 2-domain structure in which a Rossmann-fold NAD(P)-binding domain is inserted within the linear sequence of a catalytic domain of a related structure.
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