This entry represents the C-terminal domain of aspartate dehydrogenases that belong to a unique class of amino acid dehydrogenases. The structure of Thermotoga maritima TM1643 has been found to contain an N-terminal Rossmann fold domain (which binds the NAD(P)+ cofactor) and a C-terminal alpha/beta domain [1]. Enzymatic characterisation of TM1643 revealed that it possesses NAD or NADP-dependent dehydrogenase activity toward L-aspartate but no aspartate oxidase activity [1]. Members of this group share some structural similarity to several other NAD(P)+-dependent oxidoreductases, including inositol 1-phosphate synthase, dihydrodipicolinate reductase, and ASA-DH [1]. It has been proposed that in Thermotoga maritima, TM1643 catalyses the first reaction of de novo biosynthesis of NAD from aspartate, and it produces iminoaspartate required for this pathway.

1: Aspartate dehydrogenase, a novel enzyme identified from structural and functional studies of TM1643. Yang Z, Savchenko A, Yakunin A, Zhang R, Edwards A, Arrowsmith C, Tong L; J Biol Chem. 2003;278:8804-8808. PMID:12496312