Department of Biochemistry & Molecular Biology , Oregon Health & Science University , Portland , Oregon 97239 , United States.
Department of Chemistry , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States.
J Am Chem Soc. 2018 Dec 19;140(50):17389-17393. doi: 10.1021/jacs.8b11037. Epub 2018 Dec 6.
FeMbs are structural and functional models of native bacterial nitric oxide reductases (NORs) generated through engineering of myoglobin. These biosynthetic models replicate the heme-nonheme diiron site of NORs and allow substitutions of metal centers and heme cofactors. Here, we provide evidence for multiple NOR turnover in monoformyl-heme-containing FeMb1 proteins loaded with Fe, Co, or Zn metal ions at the Fe site (Fe/Co/Zn-FeMb1(MF-heme)). FTIR detection of the ν(NNO) band of NO at 2231 cm provides a direct quantitative measurement of the product in solution. A maximum number of turnover is observed with Fe-FeMb1(MF-heme), but the NOR activity is retained when the Fe site is loaded with Zn. These data support the viability of a one-electron semireduced pathway for the reduction of NO at binuclear centers in reducing conditions.
FeMbs 是通过肌红蛋白工程生成的天然细菌一氧化氮还原酶 (NORs) 的结构和功能模型。这些生物合成模型复制了 NORs 的血红素-非血红素双核铁中心，并允许金属中心和血红素辅基的取代。在这里，我们提供了证据，证明在单甲酰基血红素含有 FeMb1 蛋白中，多个 NOR 周转，该蛋白在 Fe 位点（Fe/Co/Zn-FeMb1（MF-heme））加载 Fe、Co 或 Zn 金属离子。FTIR 在 2231 cm 处检测到 ν（NNO）带的 NO 提供了溶液中产物的直接定量测量。在 Fe-FeMb1（MF-heme）中观察到最大数量的周转，但当 Fe 位点加载 Zn 时，NOR 活性仍然保留。这些数据支持在还原条件下双核中心还原 NO 的单电子半还原途径的可行性。
