The structure and dynamics of the Fe–CO bond in myoglobin

Abstract

This paper is a review of our recent work on the structure and dynamics ofthe Fe–CO bond in carbonmonoxy myoglobin (MbCO), performed usingdensity functional theory, Car–Parrinello molecular dynamics and hybridquantum mechanics/molecular mechanics approaches. The results of theseinvestigations have served to shed light onto one of the long standingquestions in myoglobin research: whether the protein discriminates the COligand with respect to O2 by distorting the FeCO bond. The calculationsshow that both in the gas phase and in the protein the Fe–CO bond isessentially linear and therefore exclude the hypothesis that the CO in MbCO issterically hindered. In contrast, hydrogen bonding between the O2 ligandand the His64 residue easily explains the protein discrimination for CO.