Renormalization of myoglobin-ligand binding energetics by quantum many-body effects.
We carry out a first-principles atomistic study of the electronic mechanisms of ligand binding and discrimination in the myoglobin protein. Electronic correlation effects are taken into account using one of the most advanced methods currently available, namely a linear-scaling density functional theory (DFT) approach wherein the treatment of localized iron 3d electrons is further refined using dynamical mean-field theory. This combination of methods explicitly accounts for dynamical and multireference quantum physics, such as valence and spin fluctuations, of the 3d electrons, while treating a significant proportion of the protein (more than 1,000 atoms) with DFT. The computed electronic structure of the myoglobin complexes and the nature of the Fe-O2 bonding are validated against experimental spectroscopic observables. We elucidate and solve a long-standing problem related to the quantum-mechanical description of the respiration process, namely that DFT calculations predict a strong imbalance between O2 and CO binding, favoring the latter to an unphysically large extent. We show that the explicit inclusion of the many-body effects induced by the Hund's coupling mechanism results in the correct prediction of similar binding energies for oxy- and carbonmonoxymyoglobin.
['Weber|Cédric|C|', 'Cole|Daniel J|DJ|', "O'Regan|David D|DD|", 'Payne|Mike C|MC|']
D000327:Adsorption D000818:Animals D004583:Electrons D008024:Ligands D056004:Molecular Dynamics Simulation D009211:Myoglobin D010100:Oxygen D011485:Protein Binding D011789:Quantum Theory D013816:Thermodynamics D014025:Titanium D014466:Ultraviolet Rays D014867:Water
metalloprotein natural bond orbitals optical absorption quantum-mechanical simulation strong correlation