Photoreactions of furocoumarins with biomolecules

Cadet, Jean; Vigny, Paul; Midden, W. Robert

doi:10.1016/1011-1344(90)85090-j

Cited by 72 publications

(95 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…16 Another explanation is that the triplet state reacts in less than 200 ns with quasi unit efficiency to yield cyclobutane dimers, since T<>T are known to be formed under triplet photosensitization conditions. 1 The data presently available do not allow us to favor one of the above hypotheses. 10 and 4600 M -1 cm -1 , 14 respectively.…”

Section: Figurementioning

confidence: 95%

Time-Resolved Study of Thymine Dimer Formation

2005

View full text Add to dashboard Cite

The formation of thymine dimers in the single-stranded oligonucleotide, (dT)20, is studied at room temperature by laser flash photolysis using 266 nm excitation. It is shown that the (6-4) adduct is formed within 4 ms via a reactive intermediate. The formation of cyclobutane dimers is faster than 200 ns. The overall quantum yield for the (6-4) formation is (3.7 ± 0.3) × 10-3, and that of the cyclobutane dimers is (2.8 ± 0.2) × 10-2. No triplet absorption is detected, showing that either the intersystem crossing yield decreases by 1 order of magnitude upon oligomerization (<1.4 × 10-3) or the triplet state reacts with unit efficiency in less than 200 ns to yield cyclobutane dimers.

show abstract

Section: Figurementioning

confidence: 95%

Time-Resolved Study of Thymine Dimer Formation

2005

View full text Add to dashboard Cite

show abstract

“…6,7,8 UV radiation can stimulate cycloaddition photoreactions in DNA molecules, generating photodimers and photoadducts. 7,9,10,11 Among the photodimers (cyclobutane pyrimidine dimers, CPDs), the most common lesion involving a single DNA strand corresponds to the dimerization of two stacked thymine molecules. On the other hand, the cycloaddition of two cytosine molecules known as cytosine adducts is the photoadduct of major impact.…”

Section: Introductionmentioning

confidence: 99%

“…85,86,87,88,89,90,91,92,93,94,95,96 Shortened fluorescence lifetimes in alternating DNA duplexes poly(dGdC)·poly(dGdC) relative to the G and C mononucleotides have been measured experimentally by using fluorescence upconversion spectroscopy, 86 indicating that proton/hydrogen transfer could be relevant, as suggested by theoretical calculations. 85 On the other hand, transient absorption measurements have showed ground-state recovery in the related d(GC) 9 ·d(GC) 9 DNA double strand an order of magnitude slower than in the monomeric nucleotides, suggesting excited-state decays driven by the formation of π-stacked excited-state species (or exciplexes) and not via interstrand proton/hydrogen transfer. 89 In this line, a combined experimental and time-dependent density functional theory (TD-DFT) study on the GC base pair in solution with CHCl 3 has also pointed out to a non-efficient process in solution.…”

Section: Introductionmentioning

confidence: 99%

Proton/Hydrogen Transfer Mechanisms in the Guanine–Cytosine Base Pair: Photostability and Tautomerism

Sauri

Gobbo

Serrano-Pérez

et al. 2012

J. Chem. Theory Comput.

View full text Add to dashboard Cite

Proton/hydrogen-transfer processes have been broadly studied in the last fifty years to explain the photostability and the spontaneous tautomerism in the DNA base pairs. In the present study, the CASSCF/CASPT2 methodology is used to map the two-dimensional potential energy surfaces along the stretched NH reaction coordinates of the guanine-cytosine (GC) base pair. Concerted and stepwise pathways are explored initially in vacuo and three mechanisms are studied: the stepwise double proton transfer, the stepwise double hydrogen transfer, and the concerted double proton transfer. The results are consistent with previous findings related to the photostability of the GC base pair and a new contribution to tautomerism is provided. The C-based imino-oxo and imino-enol GC tautomers, which can be generated during the UV irradiation of the Watson-Crick base pair, have analogous radiationless energy-decay channels to those of the canonical base pair. In addition, the C-based imino-enol GC tautomer is thermally less stable. A study of the GC base pair is carried out subsequently taking into account the DNA surroundings in the biological environment. The most important stationary points are computed using the quantum mechanics/molecular mechanics (QM/MM) approach, suggesting a similar scenario for the proton/hydrogen-transfer phenomena in vacuo and DNA. Finally, the static model is complemented by ab initio dynamic simulations, which show that vibrations at the hydrogen bonds can indeed originate hydrogen-transfer processes in the GC base pair. The relevance of the present findings for the rationalization of the preservation of the genetic code and mutagenesis is discussed.

show abstract

“…It is interesting to note that both the A . T imino protons at the Dewar lesion site were not hydrogen bonded, while the previous results [I [2][3][4][5][6][7][8][9][10][11][12][13][14] suggested that the Dewar photoproduct might cause less distortion of B-DNA compared with the (6-4) adduct. It is possible that the lack of hydrogen bonding in the Dewar lesion site allows accommodation of the mutation with less overall distortion of the B-DNA form.…”

Section: The Noes For Ts(nh)-a16(h2) and T6(nh)-a15(h2)mentioning

confidence: 40%

NMR Structural Studies of DNA Decamer Duplex Containing the Dewar Photoproduct of Thymidylyl(3′→5′)Thymidine

Hwang¹,

Kim²,

Choi³

1996

European Journal of Biochemistry

View full text Add to dashboard Cite

The single-stranded deoxynucleotide decamer containing a site-specific Dewar valence isomer of the (6-4) adduct of thymidylyl (3'-S')-thymidine was generated by direct photolysis of d(CGCATTACGC) with UV-B and UV-C irradiation. The conformation of the Dewar-photomodified deoxyoligonucleotide duplex, (C1 -G2-C3-A4-TS[DW]T6-A7-C8-G9-C10) . (GI 1 -C12-G13-T14-A1S-A16-T17-G18-C19-G20),has been studied by one-and two-dimensional NMR spectroscopy. While the eight of the ten completnentary nucleotides form Watson-Crick-type hydrogen bonding, the S'-TpT-3' bases of the Dewar lesion show no evidence of complementary hydrogen bonding formation to each other. The Dewar covalent linkage for the adjacent pyrimidine base leads to unusual base stacking, which is different from that of normal B-DNA. Unusual NOES indicate that the formation of a Dewar photoproduct in the B-DNA duplex is likely to alter its local and global structures. Also, detailed NMR data show that the base pairing and stacking of the Dewar-photoproduct-containing decamer duplex differ from that of the (6-4)-adductcontaining decamer duplex, suggesting that isomerization of the (6-4) adduct to its Dewar form induces a substantial change in the structure of the oligonucleotide duplex.Keywodr : Dewar valence isomer; (6-4) adduct; photochemically-modified oligomer; photoisomerization; NMR The major ultraviolet-light-induced photoproducts of DNA are the cis-syn and tmns-syn cyclobutane pyrimidine dimers, (6-4) adduct and Dewar photoproducts of dipyrimidine sites; of these, the cis-syn cyclobutane diiner and (6-4) photoproducts are thought to be responsible for much of the lethal, mutagenic, and carcinogenic effects [I -41. As a result, much work and debate have been focused on correlating the presence of a cis-syn photodimer and a (6-4) adduct with ultraviolet-light-induced mutations [ S , 61. The (6-4) adducts might be unstable in sunlight, being converted to their Dewar valence isomers via the absorption of UV-B (280-320 nm) light [7, 81. Therefore, the Dewar isomers of (6-4) adducts may play an important role in cytotoxicity and mutation i n skin cells exposed to solar light. Definition.It has been reported that the biological properties of the thymine Dewar photoproduct are different from those of the thymine (6-4) adduct. The antibody assays of a dinucleotide photoproduct antigen suggested that the antibodies elicited by the (6-4) adduct did not recognize the Dewar photoproduct due to different a conformation of the pyrimidinone ring, subsequently resulting in the high degree of discrimination by being the major antigenic determinant or by influencing the overall conformations of the two photoproducts 191. Recent evidence has suggested that the (6-4) adduct induced a highly specific mutation whereas the Dewar isomer induced a broader range of mutation [I 01, indicating that mutagenic properties of the two photoproducts contrast with each other. Enzyme repair rates of a 49-residue oligonucleotide containing site-specific thymine photoproducts were reported to...

show abstract

Photoreactions of furocoumarins with biomolecules

Cited by 72 publications

References 40 publications

Time-Resolved Study of Thymine Dimer Formation

Time-Resolved Study of Thymine Dimer Formation

Proton/Hydrogen Transfer Mechanisms in the Guanine–Cytosine Base Pair: Photostability and Tautomerism

NMR Structural Studies of DNA Decamer Duplex Containing the Dewar Photoproduct of Thymidylyl(3′→5′)Thymidine

Contact Info

Product

Resources

About