Reaction of cis-3-chloroacrylic acid dehalogenase with an allene substrate, 2,3-butadienoate: hydration via an enamine.
Reaction of cis-3-chloroacrylic acid dehalogenase with an allene substrate, 2,3-butadienoate: hydration via an enamine.
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DOI：
10.1021/ja206873f
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发表时间：
2012-01-11
影响因子：
15
通讯作者：
Whitman, Christian P.
中科院分区：
文献类型：
--
作者：
Schroeder, Gottfried K.;Johnson, William H., Jr.;Huddleston, Jamison P.;Serrano, Hector;Johnson, Kenneth A.;Whitman, Christian P.
顺式-3-氯丙烯酸脱卤酶（cis-CaaD）催化顺式-3-卤代丙烯酸酯水解脱卤生成丙二酸半醛。该酶处理其他底物，包括丙二烯（2，3-丁二烯酸）以产生乙酰乙酸。在使用该丙二烯的顺式-CaaD催化的反应的立体化学分析过程中，在NaBH 4存在下，通过还原共价酶-底物键，酶意外地失活。共价修饰是令人惊讶的，因为cis-CaaD脱卤的累积证据有利于涉及Pro-1介导的直接底物水合的机制。然而，随后的机制，预稳态和全过程动力学实验的结果是一致的，其中Pro-1和丙二烯之间的烯胺形成的机制。烯胺或亚胺互变异构体的水解产生乙酰乙酸酯。亚胺物质的还原可能是观察到的酶失活的原因。这是第一次报道观察到的互变异构酶超家族成员的共价催化功能。这一结果可能表明，cis-CaaD催化的cis-3-卤代丙烯酸酯的脱卤反应中的一部分也通过共价催化进行。
cis -3-Chloroacrylic acid dehalogenase (cis-CaaD) catalyzes the hydrolytic dehalogenation of cis-3-haloacrylates to yield malonate semialdehyde. The enzyme processes other substrates including an allene (2,3-butadienoate) to produce acetoacetate. In the course of a stereochemical analysis of the cis-CaaD-catalyzed reaction using this allene, the enzyme was unexpectedly inactivated in the presence of NaBH4 by the reduction of a covalent enzyme-substrate bond. Covalent modification was surprising because the accumulated evidence for cis-CaaD dehalogenation favored a mechanism involving direct substrate hydration mediated by Pro-1. However, the results of subsequent mechanistic, pre-steady state and full progress kinetic experiments are consistent with a mechanism in which an enamine forms between Pro-1 and the allene. Hydrolysis of the enamine or an imine tautomer produces acetoacetate. Reduction of the imine species is likely responsible for the observed enzyme inactivation. This is the first reported observation of a tautomerase superfamily member functioning by covalent catalysis. The result may suggest that some fraction of the cis-CaaD-catalyzed dehalogenation of cis-3-haloacrylates also proceeds by covalent catalysis.
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DOI：
10.1073/pnas.69.12.3506
发表时间：
1972-01-01
影响因子：
11.1
作者：
HOUMARD, J;DRAPEAU, GR
通讯作者：
DRAPEAU, GR
DOI：
10.1099/00221287-137-8-2025
发表时间：
1991-08-01
期刊：
JOURNAL OF GENERAL MICROBIOLOGY
影响因子：
--
作者：
HARTMANS, S;JANSEN, MW;DEBONT, JAM
通讯作者：
DEBONT, JAM
影响因子：
64.8
作者：
Ho, Meng-Chiao;Menetret, Jean-Francois;Allen, Karen N.
通讯作者：
Allen, Karen N.
影响因子：
2.9
作者：
Johnson, Kenneth A.;Simpson, Zachary B.;Blom, Thomas
通讯作者：
Blom, Thomas
影响因子：
4.8
作者：
de Jong, RM;Brugman, W;Dijkstra, BW
通讯作者：
Dijkstra, BW