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THE EFFECT OF DARK COMPLEXING ON THE PHOTOSENSITIZED FORMATION OF 8‐METHOXYPSORALEN CROSS‐LINKS WITH DNA*
Author(s) -
Grossweiner L. I.,
Sherman W. V.
Publication year - 1980
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.1751-1097.1980.tb04042.x
Subject(s) - nucleotide , photosensitivity , chemistry , dna , kinetics , fluence , biophysics , photochemistry , biochemistry , biology , organic chemistry , optics , gene , ion , physics , quantum mechanics
— The near‐UV dose at 365 nm required for the formation of 8‐methoxypsoralen (8‐MOP) cross‐links with calf thymus DNA was found to be insensitive to the concentration ratio of nucleotides to 8‐MOP over the range 100:1 to 5:1. The proposed explanation is that only the dark‐complexed 8‐MOP contributes to the photosensitized formation of monoadducts and cross‐links. A kinetics analysis indicates that the fluence required for cross‐linking should be inversely proportional to the square root of the fraction of dark‐complexed 8‐MOP per nucleotide (the binding ratio), a quantity that is insensitive to the ratio of nucleotides to 8‐MOP. These findings predict a small dependence of photosensitivity on the total 8‐MOP concentration in cellular systems in which cross‐links are the major lethal lesion.