Comparison of the effects of lower monohydric alcohols and inositol hexaphosphate on the oxidation of hemoglobin by menadione.

Analyses of optical absorption spectra show that the lower monohydric alcohols (methanol, ethanol, 1- and 2-propanol and 1-butanol) exert two distinct effects upon the oxidation of oxyhemoglobin by menadione. As chain length increases from one to three carbons, the rate of oxidation decreases. In contrast, as chain length increases, hemichrome production is enhanced along with the tendency for the oxidized hemoglobin to precipitate. Inositol hexaphosphate, which shifts the hemoglobin-oxygen dissociation curve far to the right, also increases the rate of oxidation. However, the ability of methanol and ethanol to alter oxidation rates is greater than that of IHP, and does nor correlate with their effect on oxygen affinity. The effect of these alcohols on rate of oxidation appears related primarily to their capacity for direct binding to the ferric iron-heme complex as it forms. Increased hemichrome formation, in higher alcohols, and subsequent precipitation, is primarily a solvent effect associated with increasing hydrophobicity. Menadione-induced oxidation may require deoxyhemoglobin in the presence of a small amount of oxygen in order to proceed.