Opine dehydrogenases catalyze the NAD(P)H-dependent reversible reaction to form opines that contain two asymmetric centers exhibiting either (L,L) or (D,L) stereochemistry. The first structure of a (D,L) superfamily member, N-(1-D-carboxylethyl)-L-norvaline dehydrogenase (CENDH) from Arthrobacter sp. strain 1C, has been determined at 1.8 Ã
resolution and the location of the bound nucleotide coenzyme has been identified. Six conserved residues cluster in the cleft between the enzyme's two domains, close to the nucleotide binding site, and are presumed to define the enzyme's catalytic machinery. Conservation of a His-Asp pair as part of this cluster suggests that the enzyme mechanism is related to the 2-hydroxy acid dehydrogenases. The pattern of sequence conservation and substitution between members of this enzyme family has permitted the tentative location of the residues that define their differential substrate specificities.
奥平脱氢酶催化
NAD(P)H依赖的可逆反应,形成含有两个不对称中心的奥平,表现出(L,L)或(D,L)立体
化学。Arthrobacter sp. 1C菌株的N-(1-D-羧基乙基)-
L-正缬氨酸脱氢酶(CENDH)是(D,L)超家族成员中的第一个结构,其结构以1.8 Å的分辨率测定,并确定了结合的核苷酸辅酶的位置。六个保守残基簇位于酶的两个结构域之间的裂隙中,靠近核苷酸结合位点,被认为是酶的催化机制。作为该簇的一部分,His-Asp对的保守性表明酶的机制与2-羟基酸脱氢酶有关。该酶家族成员之间的序列保守性和替代模式允许确定残基的临时位置,这些残基决定了它们不同的底物特异性。