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Ethidium bromide–DNA complex: Wavelength dependence of pyrimidine dimer inhibition and sensitized fluorescence as probes of excited states
Author(s) -
Sutherland J. C.,
Sutherland B. M.
Publication year - 1970
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1970.360090603
Subject(s) - chemistry , singlet state , ethidium bromide , photochemistry , pyrimidine dimer , dimer , fluorescence , singlet fission , excited state , bromide , dna , atomic physics , dna damage , optics , physics , biochemistry , organic chemistry
Ethidium bromide inhibits the formation of ultraviolet‐induced pyrimidine dimers in DNA. The efficiency of dimer inhibition increases with increasing energy of the exciting photons. The efficiency of energy transfer from the DNA singlet to the dye singlet, as monitored by sensitized fluorescence, is independent of wavelength. The efficiency of singlet–singlet transfer agrees with that for dimer inhibition at photon energies corresponding to excitation of the lowest singlet state of DNA. Our results support a model in which dimers are formed both directly from the singlet state and also from the triplet state, with triplets arising from higher vibrational levels of the singlet.