EFFECT OF SOME MONOHYDRIC ALCOHOLS ON THE OXYGEN-AFFINITY OF HEMOGLOBIN - RELEVANCE OF SOLVENT DIELECTRIC-CONSTANT AND HYDROPHOBICITY

We studied the effect of methanol, ethanol, iso‐propanol, and n‐propanol on the reaction of hemoglobin with oxygen. The oxygen affinity was found to decrease with increasing alcohol concentration and alkyl group size; no detectable effect on Hill's constant was found. Difference spectroscopy indicated KR not to be affected by the presence of alcohols; the lowered affinity was then attributed to an altered equilibrium between T and R conformations of hemoglobin. The results have been analyzed in such a way as to allow separation of electrostatic contributions to free energy difference between the T and R states from nonelectrostatic ones. The nonelectrostatic term has been attributed to protein–solvent hydrophobic interactions. Values of hydrophobic free energy are in good agreement with analogous data estimated by correlating different results previously reported in the literature. Copyright © 1979 John Wiley & Sons, Inc.