FLAVIN‐SENSITIZED PHOTOCHEMICALLY INDUCED DYNAMIC NUCLEAR POLARIZATION DETECTION OF PYRIMIDINE DIMER RADICALS

R. F. Hartman, S. D. Rose, P. J.W. Pouwels, R. Kaitein*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

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 pKa values for thymine dimer suggested that principally the dideprotonated dimer undergoes electron abstraction by the excited flavin.

Original languageEnglish
Pages (from-to)305-310
Number of pages6
JournalPhotochemistry and Photobiology
Volume56
Issue number3
DOIs
Publication statusPublished - 1 Jan 1992
Externally publishedYes

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