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 protec
tion increased as a function of GSH concentration. Above 10 mM the pro
tection remained constant and less than expected on the basis of scave
nging/quenching of O-1(2), in contrast to the protection offered by so
dium-azide. Especially at the higher concentrations of GSH the protect
ion 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 im
portant range (0.1-10 mM) GSH is able to protect efficiently against O
-1(2)-induced inactivating DNA damage.