The kinetics of triplet state quenching of 3,3',4,4'-benzophenone tetracarboxylic acid (BPTC) by DNA bases adenine, adenosine, thymine, and thymidine has been investigated in aqueous solution using time-resolved laser flash photolysis. The observation of the BPTC ketyl radical anion at λ(max) = 630 nm indicates that one electron transfer is involved in the quenching reactions. The pH-dependence...

The functional significance of a lac operator constitutive mutation has been determined. The transition adenine-thymine to guanine-cytosine was shown to be a constitutive mutation simply because thymine contains the functionally important 5-methyl group whereas cytosine does not. The remainder of the base pair is of no consequence. The experimental approach was to synthesize various modified op...

The crystal structure of a DNA duplex dodecamer d(CGCAAAAATGCG) and its complementary strand has been determined at 2.6-A resolution. Although our goal was to deduce the structural features of the static bending of the helical axis exhibited by adenine-tract structures in solution, we conclude that the overall bend of 20 degrees in the direction of the major groove observed here arises from the...

A simple Langevin approach is used to study stationary properties of the Peyrard-Bishop-Dauxois model for DNA, allowing known properties to be recovered in an easy way. Results are shown for the denaturation transition in homogeneous samples, for which some implications, so far overlooked, of an analogy with equilibrium wetting transitions are highlighted. This analogy implies that the order pa...

we have performed quantum-chemical ab initio in various basis sets at the hartree-fock andb3lyp levels for adenine and thymine with the program gaussian98. the dipole,quadrupole, octapole and hexadecapole moments and primitive in nine basis sets for thesemolecules are presented. the most stabilized forms of these molecules are observed in 6-311++g** basis set. we have evaluated coefficient hybr...

The shape of the barrier for the H transfer between the normal and tautomeric forms have been determined for the adenine and thymine molecules. The correlations for several singlet and triplet states has been calculated using the CNDO/2-CI method. The relative stability between both conformations and the agreement with some experimental values is also discussed.

The complex question of the biosynthetic origin of nucleic acid purines has been approached from a number of directions. The elaboration of the over-all picture for a single organism has obvious advantages, and the experiments reported here represent a study in that direction with Lactobacillus casei as the test organism. Extensive information regarding purine utilization by L. casei is availab...

A sensitive, selective and reliable liquid chromatography-mass spectrometry coupled with electrospray ionization interface method for simultaneous separation and determination of thymine, adenine, adenosine and cordycepin in Cordyceps sinensis has been established. The optimum separation for these analytes was achieved using a gradient elution system and a 2.0 x 150 mm Shimadzu VP-ODS column. 2...

The interaction of spermine and its analogue, 1-naphthyl acetyl spermine with four double stranded DNA polynucleotides has been studied to understand the structural and thermodynamic basis of the binding. The efficacy and specificity of DNA binding of this analogue has not yet been revealed. The energetics of the interaction was studied by isothermal titration calorimetry and differential scann...

In this paper we report the synthesis of three families of new amidine–based aromatic derivatives as potential DNA minor groove binding agents for the treatment of cancer. The preparation of mono–guanidine, mono–2–aminoimidazoline and asymmetric diphenyl guanidine/2–aminoimidazoline derivatives (compounds 1a,b,c to 8a,b,c) is presented. The affinity of these substrates and of a family of mono– ...