The Influence of Solvent Viscosity on the Hemepocket Dynamics of Photolyzed Carbonmonoxy Hemoglobins.
01 January 1988
The dependence of hemepocket dynamics subsequent to carbon monoxide photolysis from human hemoglobin upon solvent viscosity has been monitored using time-resolved resonance Raman spectroscopy. Prompt (geminate) ligand recombination rates and the transient hemepocket geometry established within 10 ns after photolysis appear to be independent of solvent viscosity. The rate of relaxation of the transient geometry to an equilibrium deoxy configuration is, however, quite sensitive to viscosity. These observations suggest that the former dynamic processes result from local, internal motions of the protein, while the relaxation dynamics of the proximal hemepocket are predicted upon more global protein motions that are communicated to the solvent.