EFFECT OF TRICHLOROMETHYL AND TRICHLOROMETHYL PEROXYL FREE-RADICALS ON PROTEIN SULFHYDRYL CONTENT STUDIES IN MODEL AND IN ENZYMATIC CARBON-TETRACHLORIDE ACTIVATION SYSTEMS

The effect of trichloromethyl and trichloromethyl peroxyl free radical s on protein sulfhydryl content was studied using both, model and enzy matic activation systems. In the model system activation of CCl4 to bo th free radicals was by WC light and the target protein was either del ipidated or undelipidated albumin. Under air, the CCl3O2. radicals wer e able to significantly decrease the protein SH in both albumin prepar ations. A small but significant effect of WC alone was observed with d efatted albumin. No significant decreases in protein sulfhydryl were o bserved by . CCl3 attack on the defatted albumin. Reaction of CCl3O2. on cysteine SH led to chlroform formation indicating that a Il abstrac tion reaction is involved in the process. UV light has an own effect o n SH group content. Similar results were obtained when the interaction was with undelipidated albumin rather than with cysteine. Their forma tion significantly prevented by Trolox 1 mM in incubation mixture. Whe n the CCl2O2. were generated by liver microsomal activation of CCl4 un der air, a significant decrease in microsomal protein SH content was o bserved. NADPH also exerted an effect of its own. These decreasing eff ects were fully prevented by either Trolox or EDTA addition to incubat ion mixtures bat not. by alpha-tocopherol free or as a succinate ester . Incubation mixtures containing nuclear suspensions and NADPH led to a decrease in protein SH content. This decrease was not enhanced furth er by the presence of CCl4. No effect on the protein SH content was ob served when either mitochondrial or cytosolic fractions were employed. to attempt activation of CCl4 to . CCl3/CCl3O2. free radicals. The ab ility of CCl4 derived free radicals to decrease protein SH in liver mi crosomes could be involved in loss of activity of key SH enzymes of re levance such as microsomal calcium pump. This pump is known to be dama ged during CCl4 poisoning. This effect was blamed to initiate alterati ons in calcium homeostasis later leading to CCl4 induced liver cell de ath.