THE AMBIVALENT ROLE OF GLUTATHIONE IN THE PROTECTION OF DNA AGAINST SINGLET OXYGEN

Glutathione (GSH) was examined with respect to its ability to protect DNA against O-1(2) damage. We have found that GSH protected, at least partly, the DNA against inactivation by O-1(2). Up to 10 mM the protection increased as a function of GSH concentration. Above 10 mM the protection remained constant and less than expected on the basis of scavenging/quenching of O-1(2), in contrast to the protection offered by sodium-azide. Especially at the higher concentrations of GSH the protection against the biological inactivation is accompanied by an increase in single-strand breaks and also probably lethal base damage. However, all together the data suggest that at least in the physiologically important range (0.1-10 mM) GSH is able to protect efficiently against O-1(2)-induced inactivating DNA damage.