<i>Cis</i>−<i>Trans</i> Isomerization of a Cyclopropyl Radical Trap Catalyzed by Extradiol Catechol Dioxygenases: Evidence for a Semiquinone Intermediate
作者:Emma L. Spence、G. John Langley、Timothy D. H. Bugg
DOI:10.1021/ja9607704
日期:1996.1.1
Substrate analogues cis- and trans-2-(2,3-dihydroxyphenyl)cyclopropane-1-carboxylic acid were synthesized as probes for a semiquinone radical intermediate in the (2,3-dihydroxyphenyl)propionate 1,2-dioxygenase reaction. These analogues were found to be substrates for oxidative cleavage by extradiol dioxygenases from Escherichia coli and Alcaligenes eutrophus. The stereochemistry of the ring fission
底物类似物顺式和反式 2-(2,3-二羟基苯基) 环丙烷-1-羧酸被合成为探针用于 (2,3-二羟基苯基) 丙酸 1,2-双加氧酶反应中的半醌自由基中间体。发现这些类似物是来自大肠杆菌和富养产碱杆菌的外二醇双加氧酶氧化裂解的底物。环裂变产物的立体化学通过使用随后的水解酶 MhpC 转化为环丙烷-1,2-二羧酸进行分析,然后进行 GCMS 分析。该分析揭示了 85-94% 的反式产物和 6-15% 的顺式产物,这意味着环丙基环取代基的顺式/反式异构化在酶促转化过程中发生。这些结果与环丙基环的可逆打开一致,