(E)-4-(ALPHA-HALO-PARA-TOLYL)-2-OXO-3-BUTENOIC ACIDS INHIBIT YEAST PYRUVATE DECARBOXYLASE BY A DIVERSITY OF MECHANISMS - MULTIPLE FATE FOR THE THIAMINE-BOUND ENAMINE INTERMEDIATE
(E)-4-(ALPHA-HALO-PARA-TOLYL)-2-OXO-3-BUTENOIC ACIDS INHIBIT YEAST PYRUVATE DECARBOXYLASE BY A DIVERSITY OF MECHANISMS - MULTIPLE FATE FOR THE THIAMINE-BOUND ENAMINE INTERMEDIATE
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DOI：
10.1021/ja00206a019
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发表时间：
1989-11-22
影响因子：
15
通讯作者：
JORDAN, F
中科院分区：
文献类型：
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作者：
ANNAN, N;PARIS, R;JORDAN, F
已经合成了(E)-4-(对甲苯基)-2-氧代-3-丁烯酸及其α-(溴甲基)和α-(氯甲基)衍生物，并评估了它们与啤酒酵母丙酮酸脱羧酶的相互作用。发现对甲苯基化合物是一种慢底物。溴甲基类似物导致酶部分时间依赖性失活，但最终恢复了全部活性。该类似物被证明以酶催化的、时间依赖性的方式失去溴离子，并且在其酶催化反应中，它被定量地转化为对甲基肉桂酸。氯甲基化合物导致酶随时间失活；即使在过夜孵育后也没有恢复活性。该类似物在时间依赖性酶催化反应中释放氯离子，并以 4:6 的比例产生对（氯甲基）肉桂醛和对甲基肉桂酸。所有结果都与化合物脱羧后中心烯胺中间体的不同命运一致：（1）甲基衍生物经历正常周转； (2)对(溴甲基)衍生物脱羧得到的烯胺正常周转； (2) 对(溴甲基)衍生物脱羧衍生的烯胺经历卤化物消除，产生醌甲基化物，该醌甲基化物互变异构为2-酰基硫胺二磷酸，其在水解后再生活性酶[这种行为类似于苯甲酰甲酸脱羧酶对[对(溴甲基)苯甲酰]甲酸脱羧的报道(Reynolds， L.J.；加西亚，G.A.；Kenyon，G.L.生物化学1988，27，5530)； (3) 源自氯甲基化合物的烯胺在氯消除和转换之间分配，最重要的是，还导致不可逆失活，如先前报道的一些芳环取代的 (E)-4-苯基-2-氧代-3-丁烯酸 (Kuo, D. J.; Jordan, F. Biochemistry 1983, 22 3735)。
(E)-4-(p-Tolyl)-2-oxo-3-butenoic acid and its .alpha.-(bromomethyl) and .alpha.-(chloromethyl) derivatives have been synthesized, and their interaction with brewers'' yeast pyruvate decarboxylase was evaluated. The p-tolyl compound was found to be a slow substrate. The bromomethyl analogue led to partial time-dependent inactivation of the enzyme, but full activity was regained eventually. This analogue was shown to lose bromide ion in an enzyme-catalyzed, and time-dependent, fashion, and in its enzyme-catalyzed reaction it was converted quantitatively to p-methylcinnamic acid. The chloromethyl compound led to time-dependent inactivation of the enzyme; activity was not regained even after overnight incubation. This analogue released chloride ion in a time-dependent and enzyme-catalyzed reaction and produced p-(chloromethyl)cinnamaldehyde and p-methylcinnamic acid in a ratio of 4:6. All results are consistent with decarboxylation of the compounds followed by diverse fates for the central enamine intermediate: (1) the methyl derivative undergoes normal turnover; (2) the enamine derived from the decarboxylation of the p-(bromomethyl) derivative undergoes normal turnover; (2) the enamine derived from the decarboxylation of the p-(bromomethyl) derivative undergoes halide elimination, leading to a quinone methide that tautomerizes to a 2-acylthiamin diphosphate, which upon hydrolysis regenerates active enzyme [this behavior is analogous to that in a report on the decarboxylation of [p-(bromomethyl)benzoyl]formic acid by benzoylformate decarboxylase (Reynolds, L. J.; Garcia, G. A.; Kozarich, J. W.; Kenyon, G. L. Biochemistry 1988, 27, 5530)]; (3) the enamine derived from the chloromethyl compound is partitioned between chloride elimination and turnover and, most importantly, also leads to irreversible inactivation as reported earlier for some aromatic ring substituted (E)-4-phenyl-2-oxo-3-butenoic acids (Kuo, D. J.; Jordan, F. Biochemistry 1983, 22 3735).