Price Family Foundation of Structural Biology, Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK, 73019, USA.
Department of Chemistry and Chemical Biology, Stevens Institute of Technology, Castle Point on Hudson, Hoboken, NJ, 07030, USA.
Angew Chem Int Ed Engl. 2019 Dec 16;58(51):18598-18603. doi: 10.1002/anie.201909137. Epub 2019 Oct 31.
Some bacterial heme proteins catalyze the coupling of two NO molecules to generate N O. We previously reported that a heme Fe-NO model engages in this N-N bond-forming reaction with NO. We now demonstrate that (OEP)Co (NO) similarly reacts with 1 equiv of NO in the presence of the Lewis acids BX (X=F, C F ) to generate N O. DFT calculations support retention of the Co oxidation state for the experimentally observed adduct (OEP)Co (NO⋅BF ), the presumed hyponitrite intermediate (P )Co (ONNO⋅BF ), and the porphyrin π-radical cation by-product of this reaction, and that the π-radical cation formation likely occurs at the hyponitrite stage. In contrast, the Fe analogue undergoes a ferrous-to-ferric oxidation state conversion during this reaction. Our work shows that cobalt hemes are chemically competent to engage in the NO-to-N O conversion reaction.
一些细菌血红素蛋白能催化两个 NO 分子的偶联，生成 N O。我们之前曾报道过，血红素 Fe-NO 模型能与 NO 发生 N-N 键形成反应。现在我们证明，在路易斯酸 BX（X=F、CF ）存在下，（OEP）Co（NO）也能与 1 当量的 NO 反应，生成 N O。DFT 计算支持实验观察到的加合物（OEP）Co（NO⋅BF ）、假定的亚硝酰中间物（P ）Co（ONNO⋅BF ）以及该反应的卟啉 π-自由基阳离子副产物保持 Co 的氧化态，并且 π-自由基阳离子的形成可能发生在亚硝酰阶段。相比之下，Fe 类似物在该反应过程中经历了亚铁到高铁的氧化态转换。我们的工作表明，钴血红素在化学上有能力参与从 NO 到 N O 的转化反应。
