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FLAVIN‐SENSITIZED PHOTOCHEMICALLY INDUCED DYNAMIC NUCLEAR POLARIZATION DETECTION OF PYRIMIDINE DIMER RADICALS
Author(s) -
Hartman R. F.,
Rose S. D.,
Pouwels P. J. W.,
Kaitein R.
Publication year - 1992
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1992.tb02164.x
Subject(s) - dimer , cidnp , photochemistry , pyrimidine dimer , chemistry , flavin group , thymine , fluorescence , radical , organic chemistry , dna , physics , optics , biochemistry , dna damage , enzyme
— A photochemically induced dynamic nuclear polarization (photo‐CIDNP) study of carb‐oxymethyllumiflavin‐sensitized splitting of pyrimidine dimers has been carried out. In aqueous solution at high pH, an emission signal (δ 3.9 ppm) was observed from the dimer C(6)‐ and C(6′)‐protons of an N (l), N (1′)‐trimethylene‐bridged thymine dimer (1). The dimer photo‐CIDNP signal was seen only above pD 11.6 and was most intense at pD 12.9. Also observed were weak enhanced absorption signals from the product of splitting, trimethylenebis(thymine) (8 1.7 and 7.2 ppm). In contrast, cis , syn‐thymine dimer (3) gave no photo‐CIDNP signals from the dimer. An enhanced absorption at 1.8 ppm. however, due to the product of splitting (thymine) was observed. It was found that dimer 1 and, to a lesser extent, dimer 3 quenched flavin fluorescence. An N (3), N (3′)‐dimethylated derivative of 1, however, failed to quench flavin fluorescence. Comparison of the pD profile of the dimer photo‐CIDNP signal to the pK a values for thymine dimer suggested that principally the dideprotonated dimer undergoes electron abstraction by the excited flavin.