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Potential energy surface and moleculardynamics of MbNO: existence of an unsuspected FeON minimum

Nutt, D. R., Karplus, M. and Meuwly, M. (2005) Potential energy surface and moleculardynamics of MbNO: existence of an unsuspected FeON minimum. Journal of Physical Chemistry B, 109 (44). pp. 21118-21125. ISSN 1520-5207

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To link to this item DOI: 10.1021/jp0523975


Ligands such as CO, O2, or NO are involved in the biological function of myoglobin. Here we investigate the energetics and dynamics of NO interacting with the Fe(II) heme group in native myoglobin using ab initio and molecular dynamics simulations. At the global minimum of the ab initio potential energy surface (PES), the binding energy of 23.4 kcal/mol and the Fe-NO structure compare well with the experimental results. Interestingly, the PES is found to exhibit two minima: There exists a metastable, linear Fe-O-N minimum in addition to the known, bent Fe-N-O global minimum conformation. Moreover, the T-shaped configuration is found to be a saddle point, in contrast to the corresponding minimum for NO interacting with Fe(III). To use the ab initio results for finite temperature molecular dynamics simulations, an analytical function was fitted to represent the Fe-NO interaction. The simulations show that the secondary minimum is dynamically stable up to 250 K and has a lifetime of several hundred picoseconds at 300 K. The difference in the topology of the heme-NO PES from that assumed previously (one deep, single Fe-NO minimum) suggests that it is important to use the full PES for a quantitative understanding of this system. Why the metastable state has not been observed in the many spectroscopic studies of myoglobin interacting with NO is discussed, and possible approaches to finding it are outlined.

Item Type:Article
Divisions:Life Sciences > School of Chemistry, Food and Pharmacy > Department of Chemistry
No Reading authors. Back catalogue items
ID Code:16974
Publisher:American Chemical Society

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