Chemical bonding and quadrupole splittings of 57Fe Mössbauer spectrum in active sites of oxyhemoglobin as calculated by X α -discrete variation method

Abstract

Results of quantum-chemical X α -discrete variation method (X α -DVM) calculations of interaction parameters between iron (II) and oxygen molecule in active sites of α- and β-subunits of oxyhemoglobin are presented within three models: without extra electron and in spin-unrestricted mode (model I); without extra electron and in spin-restricted mode (model II); with extra electrons in spin-unrestricted mode (model III). The electronic structure and 57Fe quadrupole splitting ΔE Q for the active site of α- and β-subunits (within model I) and only of the α-subunit (within models II and III) of oxyhemoglobin are calculated. The differences in ΔE Q values for these three models are discussed.