Photosensitized Splitting of Pyrimidine Dimers in Dna by Indole Derivatives and Tryptophan‐containing Peptides

Charlier, Michel; Hélène, Claude

doi:10.1111/j.1751-1097.1975.tb06626.x

Cited by 64 publications

(12 citation statements)

References 28 publications

(15 reference statements)

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“…These authors have ascribed this new absorption band to a complex involving electron transfer from the indole ring to the base. Although such complexes have been proposed to account for indole sensitized pyrimidine dimer cleavage (Charlier and Helene, 1975), our kinetic data are not consistent with dihydropyrimidine formation mediated by tryptophan-pyrimidine charge transfer complexes. If these charge-transfer complexes were involved, then as either the tryptophan or uracil concentrations were increased, the rate of photochemical reactions originating from the complex would also increase.…”

Section: Initial Events In Pyrimidine Photoreductioncontrasting

confidence: 99%

Photosensitized Reduction of Pyrimidine Bases by Tryptophan*

Reeve

Hopkins

1979

Photochem & Photobiology

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Thymine and uracil were chemically altered when irradiated with UV light in aqueous solution containing tryptophan as a photosensitizer. The reaction is inhibited by oxygen and is therefore not an example of photodynamic action. Unlike the pyrimidine bases, purine bases were not altered under similar reaction conditions. Two major photoproducts were identified. One of the products was identified as the reduced base, dihydrouracil or dihydrothymine. The quantum yield for formation of dihydrouracil was 0.24 x depending upon the concentrations of uracil and the reaction temperature. Radical scavengers such as cysteine and nitrous oxide decreased the rate of dihydrouracil formation. Other indole compounds also sensitized the photoreduction of uracil, their quantum yields ranging from < 1 x lo-' for tryptamine to 1.3 x for indole-3-acetic acid. A reaction mechanism is presented whereby the pyrimidines are reduced by electron transfer from a metastable charge transfer complex originating from the first excited singlet state of tryptophan.to 13.6 x

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Section: Initial Events In Pyrimidine Photoreductioncontrasting

confidence: 99%

Photosensitized Reduction of Pyrimidine Bases by Tryptophan*

Reeve

Hopkins

1979

Photochem & Photobiology

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“…The types of complex formation which can occur and the photochemistry of these complexes are described in recent reviews (Helene et al, 1982;Htlbne and Lancelot, 1982). Helene (1973) showed that triplet energy transfer from polynucleotides to tryptophan-containing peptides can occur and Charlier and Helene (1975) showed that when DNA containing thymine dimers is irradiated in the presence of lysyl-tryptophanyl-lysine some of the dimers are monomerized as a result of electron transfer from tryptophan to the dimers. Both of these effects would be protective.…”

Section: Discussionmentioning

confidence: 99%

Far Uv Irradiation of Dna in the Presence of Proteins, Amino Acids or Peptides

Larcom

Rains

1985

Photochem & Photobiology

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Abstract— The DNA of bacteriophage SP02c12 was subjected to 254 nm irradiation in solutions containing lysozyme or histone. In these solutions, the protein‐DNA mass ratios and the ionic strengths of the solvents were varied to change the amount of protein associated with the DNA. Lysozyme‐DNA binding constants were measured under the same conditions. The sensitivity of phage DNA to biological inactivation by UV increased as the amount of lysozyme bound per DNA strand increased. Although binding constants could not be measured for the DNA‐histone interaction, this protein had a protective effect which was greater under conditions which cause enhanced binding. No crosslinking of either protein could be detected even at doses ten‐fold greater than those giving a surviving fraction of 0.01. Irradiation was also performed in the presence of various amino acids and short peptides. These were chosen to include amino acids which: (1) are positively charged, (2) absorb UV of this wavelength or (3) form UV‐induced crosslinks to DNA. None of the amino acids tested affected sensitivity of the DNA to biological inactivation. Peptides containing a UV‐absorbing amino acid and a positively charged amino acid enhanced sensitivity. For each of these peptides, a mixture of the constituent amino acids had the same effect as the peptide itself. Under the conditions used, no evidence for formation of DNA‐amino acid crosslinks was found. The results indicate that proteins and peptides can sensitize DNA to UV inactivation by mechanisms other than covalent crosslink formation. Such mechanisms could include energy or electron transfer or alterations in the conformation of the DNA.

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“…The location and magnitude of the 350--400-nm shoulder are similar to those of the absorption spectmm predicted for FADH2 (15). It has been speculated that the 300-nm peak may reflect dimer repair mediated by light-excited tryptophan residues in the protein (6 1), similar to the photosensitized splitting of dimers by tryptopham-containing peptides reported previously (62), or alternatively could reflect energy transfer from tryptophan(s) to chromophore.…”

Section: Mechanism Of Photolysismentioning

confidence: 94%

DNA Repair Enzymes

Sancar¹

1988

Annual Review of Biochemistry

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Photosensitized Splitting of Pyrimidine Dimers in Dna by Indole Derivatives and Tryptophan‐containing Peptides

Cited by 64 publications

References 28 publications

Photosensitized Reduction of Pyrimidine Bases by Tryptophan*

Photosensitized Reduction of Pyrimidine Bases by Tryptophan*

Far Uv Irradiation of Dna in the Presence of Proteins, Amino Acids or Peptides

DNA Repair Enzymes

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