Studies of Acyl-CoA Dehydrogenase Catalyzed Allylic Isomerization: A One-Base or Two-Base Mechanism?
作者:Srikanth Dakoji、Injae Shin、Donald F. Becker、Marian T. Stankovich、Hung-wen Liu
DOI:10.1021/ja962532e
日期:1996.11.13
capable of catalyzing γ-H abstraction to afford the allylic isomerization between α,β- and β,γ-enone thioesters and/or inactivation by 2- or 3-acetylenic acyl-CoA derivatives. Although a dual role has been proposed for the glutamate residue in both α- and γ-deprotonation, the existence of a second active-site basic group to mediate the observed reactions occurring at γ-C remains a feasible mechanism
酰基辅酶A脱氢酶是催化脂肪酰基硫酯底物转化为相应的α,β-烯酰辅酶A产物的黄素蛋白。已经很好地确定活性位点中的谷氨酸残基 [例如,Megasphaera elsdenii 的短链酰基辅酶 A 脱氢酶 (SCAD) 中的 E367] 负责最初的 α-质子提取。早期研究还表明,这类酶能够催化 γ-H 提取,以提供 α,β- 和 β,γ-烯酮硫酯之间的烯丙基异构化和/或通过 2-或 3-炔酰基-CoA 衍生物失活. 尽管已经提出谷氨酸残基在 α- 和 γ-去质子化中的双重作用,但第二个活性位点碱性基团的存在来介导在 γ-C 发生的观察到的反应仍然是一个可行的机制。为了区分这两种可能性,我们制备了一些含有环氧乙烷的酰基辅酶A衍生物,旨在捕获α-和/或γ-C附近的活性位点碱基。它...