Differences of the quadrupole splitting and iron electronic structure for the heme models for α and β subunits in deoxyhemoglobin and for deoxymyoglobin: Quantum-chemical calculations by the DFT-DVM method

Abstract

The quantum-chemical calculation of the iron electronic structure and 57Fe quadrupole splitting have been performed by the DFT-DVM method for rough heme models for α and β subunits in deoxyhemoglobin and for deoxymyoglobine, which take into account stereochemical differences of the active cites in native proteins. The calculations revealed differences in the temperature dependences of quadrupole splitting for the three models, indicating sensitivity of the quadrupole splitting and Fe(II) electronic structure to small stereochemical variations in the nearest iron environment. The theoretical results confirmed the possibility of approximating experimental Mossbauer spectra of tetrameric hemoglobins with allowance for the nonequivalence of the Fe(II) electronic structure in nonidentical subunits.