The Reaction Path of Product Release in NO Detoxification at the Active Site of Truncated Hemoglobin N in MCSCF Approach

Abstract

The Multi-Configurational Self-Consistent Field approach with the geometry optimization was applied to the calculation of electronic properties of active site of heme core of truncated hemoglobin N, with the inclusion of [ONOO] functional group and two water molecules. The localized molecular orbitals are employed as a starting set. Two subspaces of full interaction have been used by the construction of MCSCF wavefunction. The first one includes 3d orbitals of iron atom, and the second contains bonding and antibonding molecular orbitals of peroxynitrite with one unshared electronic pair of the O2 fragment. The reaction is characterized by two transition states; the products are nitrate anion and one unbound water molecule. There arise an evidence of NO2 and NO radicals as the reaction products.