Role of water and ethanol radicals in the radiation destruction of human deoxyhemoglobin

In this study destruction of human deoxyhemoglobin (deoxy-Hb) induced by the action of primary products of water radiolysis, mainly^⋅OH,e _aq ^- , H, and of secondary ethanol radicals was investigated. The extent of destruction was estimated on the basis of absorbance ratioA ₅₀₅/A ₅₆₃ after conversion of hemoglobin into methemoglobin (MetHb) and the changes in the parameters of hemoglobin oxygenation. Deoxy-Hb solutions were irradiated under the atmosphere of argon and N₂O, in the absence and presence of ethanol. In each case the radiation-chemical yield for hemoglobin destruction $G_d = \sum\limits_i {f_i g_i } $ was determined (where :f _i-fractional efficiency of destruction by the individual radicals,g _i-fraction of radicals reacting with deoxy-Hb). Results were elaborated statistically estimating, by the method of least squares, the parameters of a multidimensional regression function which for each experiment with deoxy-Hb conc. 5 mg ml⁻¹ was of the form: $$G_d = 0.09g_{OH} + 0.018g_{e_{\overline {aq} } } - 0.099g_H + 0.03g_{R_{Et}^ \cdot } $$ . The destruction efficienciesf _⋅OH andf _{R et} ^. were statistically significant whilef _{e aq} ^- andf _H were not.