Hydrogen abstraction by 2(1H)-pyrimidinones: Another channel for secondary photochemistry of DNA photole- sions?
, Gerald Ryseck, Laura Buschhaus, and Peter Gilch
Central European Conference on Photochemistry
UV radiation can cause dimerization of adjacent pyrimidinone bases in the DNA, consequences of which can be cell death or mutations. One of these damages, the P(6-4)P photolesion, is known to be suject to secondary photochemistry, namely the Dewar valence isomerization (DVI from the singlet state.
Relying on 1-methyl-2(1H)-pyrimidinone (1MP) as a model for the "chromophore" of P(6-4)P we here investigate the fate of the triplet excitation. Triplet yields of the compound are in the order of several ten percent. CW illumination and nanosecond laser flash experiments show that triplet excited 1MP can abstract hydrogen atoms from 2-deoxy-D-ribose, a constituent of DNA. The findings complement a recent study which stated that P86-4)P might act as a triplet-triplet energy donor.