The interaction of radiation-generated radicals with myoglobin in aqueous solution: Pt. 6

G-values of the formation of ferromyoglobin (Mbsup(II)) have been determined for the continuous γ-radiolysis of N2O-saturated neutral aqueous solutions containing ferrimyoglobin (Mbsup(III)) and a series of aliphatic alcohols (RH) under conditions such that the competition for the primary radical OH radicals favors RH. A comparison of the efficiencies of reduction of Mbsup(III) by the secondary organic radicals formed via H-abstraction reactions with estimates from the literature of the fraction of radical OH attack at the C-atom α to the - OH group indicates that α-hydroxyalkyl radicals are primarily responsible for the observed reduction. Significantly lower reduction yields are observed when RH 1,2-diol, compared with the expected yields of strongly reducing 1,2-dihydroxyalkyl radicals; the initial reducing radicals convert into inactive β-alkanonyl analogues so that the reduction of Mbsup(III) is not kinetically competitive with the β-elimination process. Mbsup(III) is useful as a probe of the occurrence of slow conversion processes involving radiolytically-generated radicals. (author)