DFT Calculations for Mössbauer Properties on Dinuclear Center Models of the Resting Oxidized Cytochrome c Oxidase.

Abstract

Mössbauer isomer shift and quadrupole splitting properties have been calculated using the OLYP‐D3(BJ) density functional method on previously obtained (W.‐G. Han Du, et al., Inorg Chem. 2020, 59, 8906–8915) geometry optimized Fea3 3+−H2O−CuB 2+ dinuclear center (DNC) clusters of the resting oxidized (O state) “as‐isolated” cytochrome c oxidase (CcO). The calculated results are highly consistent with the available experimental observations. The calculations have also shown that the structural heterogeneities of the O state DNCs implicated by the Mössbauer experiments are likely consequences of various factors, particularly the variable positions of the central H2O molecule between the Fea3 3+ and CuB 2+ sites in different DNCs, whether or not this central H2O molecule has H‐bonding interaction with another H2O molecule, the different spin states having similar energies for the Fea3 3+ sites, and whether the Fea3 3+ and CuB 2+ sites are ferromagnetically or antiferromagnetically spin‐coupled.