The effect of the nucleic acid bases adenine, cytosine, thymine, uracil, and 5-bromo-uracil on the light-induced reduction of methylene blue in dimethylsulfoxide has been investigated by means of ESR and optical absorption studies. It could be shown that the nucleic acid bases act as electron acceptors. The experimentally obtained electron affinities are of the following order: cytosine > adeni...

The knowledge of the energy levels of the lowest triplet states of the DNA constituents obtained from photophysical experiments has allowed the design of a photochemical technique which introduces a specific change in the DNA structure, the dimerization of adjacent thymine residues, which, in turn, has led to important conclusions about the role of thymine dimers in the u.v. photobiology of T4 ...

Using a human cell-free extract, we have recently shown that thymine dimers are removed from DNA in oligonucleotides 27-29 nucleotides in length (Huang, J. C., Svoboda, D. L., Reardon, J. T., and Sancar, A. (1992) Proc. Natl. Acad. Sci. U. S. A. 89, 3664-3668). In this study we find that the excision reaction is dependent on ATP, the excised fragments range in length from 27-32 nucleotides, and...

A fluorescent pyrazine derivative, 3,5-diamino-6-chloro-2-pyrazine carbonitrile (DCPC), is presented as a promising light-up ligand for single-nucleotide polymorphisms (SNPs) typing. In solutions buffered to pH 7.0 (I = 0.11 M, at 5 degrees C), DCPC can bind to thymine selectively over other nucleobases opposite an abasic site in DNA duplexes (5'-GTGTG CGTTG ANA TGGAC GCAGA-3'/3'-CACAC GCAAC TX...

1-alkoxymethyl-5-alkyl-6-naphthylmethyl uracils, which are novel 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine (HEPT) analogues, were synthesized for evaluation as selective and potent nonnucleoside human immunodeficiency virus (HIV)-1 reverse transcriptase inhibitors. The anti-HIV-1 activity of these compounds was assayed in vitro using HIV-1 infected MT-4 and CEM bioassays. The EC50, CC50...

T4 endonuclease V is a DNA repair enzyme from bacteriophage T4 that catalyzes the first reaction step of the pyrimidine dimer-specific base excision repair pathway. The crystal structure of this enzyme complexed with a duplex DNA substrate, containing a thymine dimer, has been determined at 2.75 A resolution. The atomic structure of the complex reveals the unique conformation of the DNA duplex,...