The action of coenzyme B12-dependent diol dehydratase on 3,3,3-trifluoro-1,2-propanediol results in elimination of all the fluorides with formation of acetaldehyde.

IF 2.1 4区 生物学 Q4 BIOCHEMISTRY & MOLECULAR BIOLOGY
Koichi Mori, Bernard T Golding, Tetsuo Toraya
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引用次数: 0

Abstract

3,3,3-Trifluoro-1,2-propanediol undergoes complete defluorination in two distinct steps: first, the conversion into 3,3,3-trifluoropropionaldehyde catalyzed by adenosylcobalamin (coenzyme B12)-dependent diol dehydratase; second, non-enzymatic elimination of all three fluorides from this aldehyde to afford malonic semialdehyde (3-oxopropanoic acid), which is decarboxylated to acetaldehyde. Diol dehydratase accepts 3,3,3-trifluoro-1,2-propanediol as a relatively poor substrate, albeit without significant mechanism-based inactivation of the enzyme during catalysis. Optical and electron paramagnetic resonance (EPR) spectra revealed the steady-state formation of cob(II)alamin and a substrate-derived intermediate organic radical (3,3,3-trifluoro-1,2-dihydroxyprop-1-yl). The coenzyme undergoes Co-C bond homolysis initiating a sequence of reaction by the generally accepted pathway via intermediate radicals. However, the greater steric size of trifluoromethyl and especially its negative impact on the stability of an adjacent radical centre compared to a methyl group has implications for the mechanism of the diol dehydratase reaction. Nevertheless, 3,3,3-trifluoropropionaldehyde is formed by the normal diol dehydratase pathway, but then undergoes non-enzymatic conversion into acetaldehyde, probably via 3,3-difluoropropenal and malonic semialdehyde.

辅酶 B12 依赖性二元醇脱水酶对 3,3,3-三氟-1,2-丙二醇的作用会消除所有氟化物并形成乙醛。
3,3,3-三氟-1,2-丙二醇通过两个不同的步骤进行完全脱氟:首先,在依赖腺苷钴胺(辅酶 B12)的二元醇脱水酶催化下转化为 3,3,3-三氟丙醛;其次,从该醛中非酶消除所有三个氟化物,生成丙二酸半醛(3-氧代丙酸),然后脱羧为乙醛。二醇脱水酶接受 3,3,3-三氟-1,2-丙二醇作为相对较差的底物,尽管在催化过程中不会出现基于机理的酶失活现象。光学和 EPR 光谱显示,钴(II)氨基和底物衍生的中间有机自由基(3,3,3-三氟-1,2-二羟基丙-1-基)稳态形成。辅酶发生 Co-C 键均解,通过中间自由基以公认的途径启动一系列反应。然而,与甲基相比,三氟甲基的立体尺寸更大,尤其是对邻近自由基中心的稳定性有负面影响,这对二元醇脱水酶反应的机理产生了影响。不过,3,3,3-三氟丙醛是通过正常的二元醇脱水酶途径形成的,但随后可能通过 3,3-二氟丙烯醛和丙二醛半醛非酶转化为乙醛。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Journal of biochemistry
Journal of biochemistry 生物-生化与分子生物学
CiteScore
4.80
自引率
3.70%
发文量
101
审稿时长
4-8 weeks
期刊介绍: The Journal of Biochemistry founded in 1922 publishes the results of original research in the fields of Biochemistry, Molecular Biology, Cell, and Biotechnology written in English in the form of Regular Papers or Rapid Communications. A Rapid Communication is not a preliminary note, but it is, though brief, a complete and final publication. The materials described in Rapid Communications should not be included in a later paper. The Journal also publishes short reviews (JB Review) and papers solicited by the Editorial Board.
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