Danenberg P V, Danenberg K D, Cleland W W
J Biol Chem. 1978 Sep 10;253(17):5886-7.
We have synthesized phenyl adenine dinucleotide (P1-adenosine-5')-P2-(beta-D-ribofuranosylbenzene-5')-pyrophosphate (PhAD), a novel analog of pyridine nucleotide coenzymes. This compound contains a planar aromatic ring, as does NAD+, but lacks a positive charge. PhAD is an inhibitor of horse liver alcohol dehydrogenase, competitive with NADH. PhAD is very similar to NAD+ sterically since both compounds have a planar aromatic ring. However, PhAD resembles NADH in binding to the enzyme because the dissociation constants of both compounds show a parallel increase as the pH is raised, whereas those of NAD+ behave in the opposite manner. These observations indicate that the enzyme differentiates between NAD+ and NADH on the basis of the positive charge on the molecule and not the stereochemical orientation of the reduced nicotinamide ring.
我们合成了苯基腺嘌呤二核苷酸（P1 - 腺苷 - 5'）-P2 -（β - D - 呋喃核糖基苯 - 5'）- 焦磷酸（PhAD），一种新型的吡啶核苷酸辅酶类似物。该化合物含有一个平面芳香环，与NAD⁺一样，但缺少正电荷。PhAD是马肝醇脱氢酶的抑制剂，与NADH具有竞争性。PhAD在空间结构上与NAD⁺非常相似，因为这两种化合物都有一个平面芳香环。然而，PhAD在与酶结合方面类似于NADH，因为随着pH升高，这两种化合物的解离常数都呈平行增加，而NAD⁺的解离常数则表现出相反的行为。这些观察结果表明，该酶根据分子上的正电荷而非还原型烟酰胺环的立体化学取向来区分NAD⁺和NADH。
