EFFECT OF IRRADIATION ON SUB-CELLULAR PARTICLES - DESTRUCTION OF SULPHYDRYL GROUPS

Thiol groups of rat-liver nuclei, mitochondria, lysosomes, and microsomes are destroyed by irradiation in vitro with electron doses of 5-50 Kilorads. Significant destruction of thiol content occurs in all sub-cellular fractions immediately after a dose of 5 Mlorads, the percentage of -SH groups destroyed being 9.5% in the nuclei, 23% in the lysosomes, 9.1% in the mitochondria and 2.8% in the microsomes. The percentage of thiol groups destroyed increased with radiation dose in all fractions. Incubation in air or O2 at 4[degree] C, 20[degree] C or 37[degree] C after irradiation causes further destruction of sulphydryl groups, but this does not occur after incubation in N2. The destruction of -SH groups is a result of oxidation by free radicals produced in the aqueous phase and is not a result of oxidation by lipid peroxides.[long dash]Authors.