Meglioli Mirco, Sebastiani Federico, Bellei Marzia, Di Rocco Giulia, Ranieri Antonio, Bortolotti Carlo Augusto, Sola Marco, Borsari Marco, Smulevich Giulietta, Battistuzzi Gianantonio
Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia, via Campi 103, Modena 41125, Italy.
Department of Chemistry "Ugo Schiff" DICUS, University of Florence, via della Lastruccia 3, Sesto Fiorentino (FI) 50019, Italy.
Inorg Chem. 2025 May 12;64(18):9066-9083. doi: 10.1021/acs.inorgchem.5c00551. Epub 2025 May 2.
The electronic absorption, MCD, and RR spectra of the Co(III) and Co(II) derivatives of wild-type human neuroglobin (Co-WT) and its C46A/C55A mutant (Co-C46AC55A) were thoroughly investigated and compared with those of the corresponding Fe species and of the few Co-substituted heme proteins characterized so far. In both oxidation states, Co-WT and Co-C46AC55A contain a low-spin six-coordinated Co ion, whose axial coordination positions appear to be occupied by the distal and proximal histidines and whose electronic properties are scarcely affected by deletion of the C46-C55 disulfide bond. Both Co-WT and Co-C46AC55A feature negative °' values. Fe(III) to Co(III) swapping does not significantly alter the pH dependence of their spectroscopic properties and °' values, indicating that no major changes occur in their regulating molecular factors. Most importantly, Co-WT and Co-C46AC55A can catalyze the reduction of HO to H, with onset potentials and overpotentials comparable to those of Co-porphyrin/polypeptide catalysts. The electrocatalytic efficiency of Co-WT and Co-C46AC55A for the development of H is slightly lower compared to that of six-coordinated aquo-His Co-Mb, although they are less affected by the presence of dioxygen.
对野生型人神经球蛋白（Co-WT）及其C46A/C55A突变体（Co-C46AC55A）的Co（III）和Co（II）衍生物的电子吸收光谱、磁圆二色光谱和拉曼光谱进行了全面研究，并与相应的Fe物种以及迄今已表征的少数Co取代的血红素蛋白的光谱进行了比较。在两种氧化态下，Co-WT和Co-C46AC55A均含有一个低自旋六配位Co离子，其轴向配位位置似乎被远端和近端组氨酸占据，并且其电子性质几乎不受C46-C55二硫键缺失的影响。Co-WT和Co-C46AC55A均具有负的°'值。Fe（III）到Co（III）的交换不会显著改变其光谱性质和°'值对pH的依赖性，表明其调节分子因子没有发生重大变化。最重要的是，Co-WT和Co-C46AC55A可以催化HO还原为H，其起始电位和过电位与Co-卟啉/多肽催化剂相当。与六配位水合-His Co-Mb相比，Co-WT和Co-C46AC55A对H生成的电催化效率略低，尽管它们受双氧存在的影响较小。
