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Electrochemical and Spectroscopic Characterization of Co-Neuroglobin: A Bioelectrocatalyst for H2 Production

Year: 2025

Type: article

Abstract: High Resolution Image Download MS PowerPoint Slide 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 E °′ Co(III)/Co(II) values. Fe(III) to Co(III) swapping does not significantly alter the pH dependence of their spectroscopic properties and E °′ values, indicating that no major changes occur in their regulating molecular factors. Most importantly, Co-WT and Co–C46AC55A can catalyze the reduction of H 3 O + to H 2, 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 2 is slightly lower compared to that of six-coordinated aquo-His Co-Mb, although they are less affected by the presence of dioxygen.

Source: Inorganic Chemistry

DOI: 10.1021/acs.inorgchem.5c00551