Effect of Paramagnetic Ions upon Formation of Spore Photoproduct in DNA Irradiated with UV at -196°C

Abstract

Amount of “spore photoproduct” (SP) was estimated by chromatography from ³H-labeled Escherichia coli DNA irradiated with 254 nm UV at -196°C. The amount of SP was greatly reduced by the presence of triplet state quencher manganese during irradiation. Magnesium which does not quench the triplet had no effect on SP formation. These results support the view that the excited triplet state of thymine, but not singlet state, is the precursor of SP.