Oxidation of reduced glutathione by subcellular fractions of rat liver

Abstract

1. A new method was used to diminish the autoxidation of GSH. 2. The oxidation of GSH by liver homogenates was studied with regard to concentration of homogenate, concentration of GSH, time, pH and anaerobiosis. 3. GSH was oxidized by recombinations of the supernatant with microsomes and with mitochondria. Each fraction alone caused little oxidation. 4. Proteins in the supernatant were required to obtain the effect, and low-molecular-weight compounds in the same fraction increased its effect. 5. GSH diminished the formation of malonaldehyde in homogenates. 6. GSH prevented a stimulating effect of the supernatant on the formation of malonaldehyde in microsomes and in mitochondria. 7. The malonaldehyde formation in microsomes together with the supernatant did not start until the concentration of endogenous low-molecular-weight thiols had decreased to a low level. 8. It is suggested that part of the oxidation of GSH in homogenates is coupled to a mechanism that counteracts the peroxidation of membrane lipids.

Status of Lipid Peroxidation, Some Antioxidant Enzymes and Erythrocytic Fragility of Crossbred Cattle Naturally Infected with Theileria annulata

“…They reported that GPx activities in plasma and erythrocytes did not di¡er signi¢cantly between a group of cattle naturally infected with T. annulata and treated with buparvaquone and another group of uninfected, untreated controls. However, the signi¢cant rise in GPx activity in our study could be due to the fact that GPx appeared to be the major mechanism for intracellular decomposition of lipid peroxides (Christophersen, 1966;Flohe, 1971). Hafeman and colleagues (1974) also proposed that GPx played a crucial role in preventing membranes from peroxide damage induced by lipid peroxides.…”

Involvement of free radicals in parasitic infestations

“…Low G6PD activity can be followed by reduced activities of SOD and GSH-PX, because of the dependence of the activity of these enzymes on NADPH'H levels in the cell. Christophersen (1966), Flohe (1971) and Hafeman et al (1974) also proposed that GSH-PX played a crucial role in preventing membranes from peroxide damage induced by lipid peroxides. Reduced glutathione is required for the disposal of hydrogen peroxide (H 2 O 2 ) from erythrocytes by a reaction catalysed by GSH-PX.…”

Further Experiments on Lipid Peroxidation in Transplanted and Experimental Hepatomas

“…This was accompanied by a modest or no increase in GSSG. Conversion of GSH into GSSG takes place during lipid peroxidation largely through the action of glutathione peroxidase in the presence of lipid hydroperoxides (26). We might infer from these data that glutathione peroxidase activity is low in hepatomas.…”

“…GP transforms GSH into GSSG in the presence of lipid hydroperoxides, nucleotide peroxides or hydrogen peroxide. It is thought that this step is important in the destruction of free radicals in damaged tissues (26). GR reduces GSSG back to GSH in the presence of NADPH.…”