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

Mossbauer isomer shift and quadrupole splitting properties have been calculated using the OLYP-D3(BJ) density functional method on previously obtained (Han Du W-G, et al. Inorg Chem. 2020, 59, 8906-8915) geometry optimized Fe-a3(3+)-H2O-Cu-B(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 Mossbauer experiments are likely consequences of various factors, particularly the variable positions of the central H2O molecule between the Fe-a3(3+) and Cu-B(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 Fe-a3(3+) sites, and whether the Fe-a3(3+) and Cu-B(2+) sites are ferromagnetically or antiferromagnetically spin-coupled.

Automated summary

The Mossbauer isomer shift and quadrupole splitting properties of Fe-a3(3+)-H2O-Cu-B(2+) dinuclear center (DNC) clusters in the resting oxidized state of cytochrome c oxidase were calculated using the OLYP-D3(BJ) density functional method. The calculated results were consistent with experimental observations, indicating that structural heterogeneities in the DNCs may be influenced by factors such as the position of the central H2O molecule, different spin states, and the spin-coupling of Fe-a3(3+) and Cu-B(2+) sites.