Chemical Effects of γ-Irradiation of Aqueous Solutions of Heparin and Keratan Sulphate

Abstract

During γ-irradiation of dilute aqueous solutions of heparin and keratan sulphate, acid and reducing products are formed, mainly as a result of attack by OH radicals. Depolymerization to give lower dextrins also occurs without loss of sulphate groups, which results in a decrease in the dye binding ability of the polyanion. Pulse radiolysis was used to measure the rate constants for attack by OH radicals $(k_{2}=4.7\times 10^{8} M^{-1} {\rm sec}^{-1})$ and $e_{{\rm aq}}^{-} (k_{2}=3.0\times 10^{7} M^{-1} {\rm sec}^{-1})$. Oxygen exerts a protective effect which can be accounted for by the scavenging reaction $e_{{\rm aq}}^{-}+{\rm O}_{2}\rightarrow {\rm O}_{2}{}^{-}$.