Jordan F, Adams J, Farzami B, Kudzin Z H
Department of Chemistry, Rutgers, State University, Newark, New Jersey 07102.
J Enzyme Inhib. 1986;1(2):139-49. doi: 10.3109/14756368609020112.
A series of phenyl substituted E-4-phenyl-2-keto-3-butenoic acid derivatives were synthesized (p-Cl, m-Cl, p-NO2, m-NO2, o-NO2, 3,4-Cl2, 2,6-Cl2, p-CH3O, p-(CH3)2N) and tested as potential irreversible inhibitors of brewer's yeast pyruvate decarboxylase (EC 4.1.1.1). All those derivatives with electron withdrawing substituents were found to be time-dependent inactivators of the enzyme, unlike the p-CH3O- and p-(CH3)2N derivatives. Detailed kinetic studies with the m-nitro derivative (the most potent inhibitor) indicated that this compound formed reversible complexes with the enzyme at two sites (supposed regulatory and catalytic with Ki values of 0.026 and 0.13 mM, respectively) prior to irreversible inactivation of the enzyme. In addition, concurrently with the inactivation, addition of the m-NO2 derivative to the enzyme produced a new VIS absorbance with lambda max near 430 nm. This absorbance was attributed to the enzyme-bound enamine intermediate. The time course of formation and disappearance of the intermediate could be determined and provided detailed information about the mechanism of the enzyme.
合成了一系列苯基取代的E-4-苯基-2-氧代-3-丁烯酸衍生物（对氯、间氯、对硝基、间硝基、邻硝基、3,4-二氯、2,6-二氯、对甲氧基、对二甲氨基），并作为啤酒酵母丙酮酸脱羧酶（EC 4.1.1.1）的潜在不可逆抑制剂进行了测试。与对甲氧基和对二甲氨基衍生物不同，所有具有吸电子取代基的衍生物均被发现是该酶的时间依赖性失活剂。对间硝基衍生物（最有效的抑制剂）进行的详细动力学研究表明，该化合物在酶不可逆失活之前，在两个位点（推测为调节位点和催化位点，Ki值分别为0.026和0.13 mM）与酶形成可逆复合物。此外，在失活的同时，向酶中添加间硝基衍生物会产生一个新的可见吸收峰，其最大波长接近430 nm。该吸收峰归因于与酶结合的烯胺中间体。可以确定中间体形成和消失的时间进程，并提供有关酶作用机制的详细信息。
