近日，美国宾夕法尼亚州立大学教授Carsten Krebs和J. Martin Bollinger及其研究团队，报道了铁加氧酶从2-氧戊二酸中切除乙烯的杂交自由基极性途径。该研究于2021年8月12日发表于国际一流学术期刊《科学》杂志上。

结果表明，EFE通过(3S,4R)-[2H2]-2OG生成立体化学随机(顺、反等)的1,2-[²H₂]-乙烯，并将O₂的氧附加到C1衍生的双碳酸酯上，并通过与2OG或酶的修饰转化为ω-羟基化单酸产物。这些结果表明，铁(II)配位的酰基过氧碳酸酯和烷基碳酸酯中间体存在非极性自由基-极性杂化机制。该机制解释了EFE如何获取高能羧基以启动其裂解级联反应，并暗示了依赖于2OG的酶的有待发现和开发的新能力。

据介绍，微生物乙烯形成酶(EFE)将其主要代谢产物2-氧戊二酸酯(2OG)的C3-C4片段转化为同名的烯烃产品。这个反应与由相关酶促进的简单的2OG脱羧成琥珀酸有很大的不同，并引发了不同的机理假设。

附：英文原文

Title: Hybrid radical-polar pathway for excision of ethylene from 2-oxoglutarate by an iron oxygenase

Author: Rachelle Copeland, Shengbin Zhou, Irene Schaperdoth, Tokufu Kent Shoda, J. Martin Bollinger, Carsten Krebs

Issue&Volume: 2021/08/12

Abstract: Microbial ethylene-forming enzyme (EFE) converts the C3-C4 fragment of the ubiquitous primary metabolite, 2-oxoglutarate (2OG), to its namesake alkene product. This reaction is very different from the simple decarboxylation of 2OG to succinate promoted by related enzymes and has inspired disparate mechanistic hypotheses. We show that EFE produces stereochemically random (equal cis and trans) 1,2-[2H2]-ethylene from (3S,4R)-[2H2]-2OG, appends an oxygen from O2 upon the C1-derived (bi)carbonate, and can be diverted to ω-hydroxylated monoacid products by modifications to 2OG or the enzyme. These results implicate an unusual radical-polar hybrid mechanism involving iron(II)-coordinated acylperoxycarbonate and alkylcarbonate intermediates. The mechanism explains how EFE accesses a high-energy carboxyl radical to initiate its fragmentation cascade, and it hints at new capabilities of 2OG-dependent enzymes that may await discovery and exploitation.

DOI: 10.1126/science.abj4290

Source: https://science.sciencemag.org/content/early/2021/08/11/science.abj4290