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A N Veselkov

Publications and source records attributed to A N Veselkov.

At least 37 records · Page 2Linked to original sources
PubMedDate not supplied

[NMR study of complex formation of aromatic ligands with heptadeoxynucleotide 5'-d(GCGAAGC) forming stable hairpin structure in aqueous solution].

Complex formation of hairpin-producing heptadeoxynucleotide 5'-d(GCGAAGC) with aromatic molecules: acridine dye proflavine and anthracycline antibiotic daunomycin was studied by one-dimensional 1H NMR and two-dimensional correlation 1H-1H (2M-TOCSY, 2M-NOESY), 1H-31P (2M-HMBC) NMR spectroscopy (500 and 600 MHz) in aqueous solution. Concentration and temperature dependences for the chemical shifts of ligand protons were measured, molecular models of equilibrium in solution were developed, and equilibrium thermodynamic parameters for the formation of intercalation complexes were calculated. Spatial structures of dye and antibiotic complexes with the heptamer hairpin were constructed on the basis of 2M-NOE data and the calculated values of limiting chemical shifts of ligand protons.

Daunorubicin↗
PubMedDate not supplied

[Study of the interaction of proflavin with deoxytetraribonucleoside triphosphate 5'-d(ApGpCpT) in aqueous solution by uni- and two-dimensional 1H-spectroscopy].

Complex formation between acridine dye proflavine and self-complementary deoxytetraribonucleoside triphosphate 5'-d(ApGpCpT) in water-salt solution was studied by the method of one- and two-dimensional 1H-NMR spectroscopy (500 MHz). Two-dimensional homonuclear 1H-NMR spectroscopy (2D-COSY and 2D-NOESY) was used for complete assignments of proton signals of molecules in solution and for qualitative analysis of the nature of interactions between proflavine and tetranucleotide. Concentration dependences of proton chemical shifts of the molecules were measured at 293 K. Equilibrium reaction constants and limiting chemical shifts of dye protons in the complexes were determined using suggested schemes of complex formation. Based on the obtained data possible types of complexes were considered. Analysis of relative content of different types of complexes was made and special features of dynamic equilibrium were revealed as a function of correlation of dye and tetranucleotide concentrations. The most favourable structure of 1:2 complex of dye with tetranucleotide was constructed using the calculated values of induced chemical shifts of proflavine protons and 2D-NOESY spectra.

Magnetic Resonance Spectroscopy↗
PubMedDate not supplied

[Thermodynamic analysis of the interaction of the acridine dye proflavin with deoxytetranucleotides with various base sequences from (1)H-NMR data].

Temperature dependences of proton chemical shifts of the molecules in aqueous solutions of proflavine with deoxytetraribonucleoside triphosphates of different base sequence--5'-d(CGCG), 5'-d(GCGC), 5'-d(ACGT) and 5'-d(AGCT) have been studied by 500 MHz NMR spectroscopy. Methods of calculation of thermodynamical parameters of complex formation, giving an opportunity to differentiate the contributions of the reactions leading to the formation of different types of complexes in conditions of the composite equilibrium in solution, have been suggested. Enthalpies and entropies of the reactions of 1:1, 2:1, 1:2, 2:2 complexes formation between proflavine and tetranucleotides have been determined. Comparative analysis of the calculated thermodynamical parameters has been made and assumptions about the nature of intermolecular interactions responsible for the formation of dye complexes with different tetranucleotides have been proposed.

Base Sequence↗
PubMedDate not supplied

[Interaction of proflavin with deoxytetraribonucleoside triphosphate 5'-d(ApGpCpT): thermodynamic analysis from (1)H NMR data].

Temperature relationships of chemical shifts of protons of proflavin mixed with deoxytetraribonucleoside triphosphate 5'-d(ApGpCpT) in water solution were investigated on impulse NMR spectrometer (500 MHz). Procedure is suggested for calculating values of mole fractions of various associates in solution as a function against temperature. Free energies of Gibbs, entalpy and entropy were determined in the reactions of complex formation 1:1, 1:2, 2:1 of proflavin with tetranucleotide. The results point to a significant role of hydrophobic interactions during the formation of dye--tetramere duplex complexes.

Magnetic Resonance Spectroscopy↗
PubMedDate not supplied

[A stochastic model for the NMR analysis of the heteroassociation of biologically active aromatic molecules].

A stochastic model for the NMR analysis of the heteroassociation of two aromatic compounds was developed, which takes into account all physically possible reactions of association of molecules in solution. Expressions for calculating the experimentally observed proton chemical shift were obtained in the general form, and an algorithm for calculating the parameters of heteroassociation using the stochastic model was proposed. The effects of limitations of the basic and general models, as compared with the stochastic model, on the model parameters of the heteroassociation of various biologically active aromatic molecules was analyzed. It was shown that the basic model can be used with a sufficient degree of accuracy for systems with a relatively small contribution of heteroassociation reactions to the total dynamic equilibrium in solution, whereas the general model describes satisfactorily the parameters of heteroassociation practically for all systems studied.

Algorithms↗
PubMedDate not supplied

[Distinctive features of the self-association of deoxyhexanucleotide 5'-D(GpCpApTpGpC) in aqueous solution: 1H NMR analysis].

The self-association of self-complementary deoxyhexanucleotide d(GCATGC) was investigated in aqueous salt solution. Homonuclear 1H NMR correlation spectroscopy (2D-TOCSY and 2D-NOESY) was used for complete assignments of nonexchangeable protons of the hexamer. The equilibrium reaction constants and thermodynamical parameters of duplex d(GCATGC)2 formation were determined from experimental concentration and temperature dependences of proton chemical shifts of the deoxyhexanucleotide. Distinctive features of the concentration dependences in the range of small concentrations at relatively low temperatures of solution enable one to assume that one single-stranded hexamer sequence forms a compact structure (similar to a hairpin) in aqueous solution. A possible spatial hairpin structure of the hexamer was proposed. Comparative analysis of the experimental and theoretical (using the "nearest neighbor" model) thermodynamical parameters of duplex formation was made.

Base Sequence↗
PubMedDate not supplied

[1H NMR analysis of the complex formation of aromatic molecules of antibiotic and vitamin in aqueous solution: heteroassociation of actinomycin D and flavin mononucleotide].

The molecular mechanism of the combined action of antibiotic and vitamin was studied by NMR spectroscopy. The heteroassociation of the antitumor antibiotic actinomycin D and flavin mononucleotide was investigated as a function of concentration and temperature by 500 MHz 1H NMR spectroscopy. The equilibrium association constant, the thermodynamic parameters (deltaH, deltaS) of heteroassociation of actinomycin D with flavin mononucleotide, and the limiting values of proton chemical shifts in the heterocomplex were determined from the concentration and temperature dependences of proton chemical shifts of molecules. The most favorable structure of the 1:1 actinomycin D-flavin mononucleotide heteroassociation complex was determined using both the molecular mechanics methods (X-PLOR software) and the limiting values of proton chemical shifts of the molecules. In the calculated structure, the planes of the chromophores of actinomycin D and flavin mononucleotide molecules in the 1:1 heterocomplex are parallel and separated from each other by a distance of about 0.34 nm. At the same time, there is a probability of formation of intermolecular hydrogen bonds in the calculated structure of 1:1 actinomycin D-flavin mononucleotide complex. The analysis of the results obtained suggests that aromatic molecules of vitamins, e.g., flavin mononucleotide, can form energetically favorable heterocomplexes with aromatic antitumor antibiotics in aqueous solution, modulating thereby the efficacy of their medical and biological action.

Anti-Bacterial Agents↗
PubMedDate not supplied

[Structural analysis of the complex of phenoxazone antibiotic actinocyl-bis-(2-deoxytetranucleotide 5'-d(TpGpCpA) by the methods of two dimensional 1H-NMR-spectroscopy and molecular mechanics].

The spatial structures of intercalated complexes of synthetic phenoxazone antibiotic actinocyl-bis-(2-dimethylaminoethyl) amide with self-complementary deoxytetranucleotide 5'-d(TpGpCpA) have been investigated. Analysis has been made using two-dimensional NMR (2D-NOESY) data in aqueous solution and molecular mechanics simulation. Distinctive features of the conformation of drug-DNA complexes have been determined at two possible orientations of the chromophore of phenoxazone antibiotic at the intercalation site.

Anti-Bacterial Agents↗
PubMedDate not supplied

[Determination of thermodynamic parameters of proflavine interaction with ribodinucleoside monophosphates CpG and PpC in an aqueous solution from data of proton magnetic resonance].

The temperature dependence of proton chemical shifts of proflavine in solution with isomeric ribodinucleoside monophosphates CpG and GpC has been studied. A scheme of calculation of thermodynamic parameters of dye aggregation and 1 : 1 and 1 : 2 complexes formation with dinucleotides has been proposed. The Gibbs' free energy, enthalpy and entropy of these reactions have been determined. It is concluded that hydrophobic interactions play an important part when 1 : 2 complex of proflavine with ribonucleosides is being formed.

Acridines↗
PubMedDate not supplied

[Study of the interaction of proflavine and isomeric diribonucleoside monophosphates CpG and GpC by proton magnetic resonance].

A comparative study of the interaction of proflavine with isomeric diribonucleoside monophosphates CpG and GpC has been made by the method of 1H NMR (270 MHz). A method of calculation of the parameters of complex formation from the concentration dependences of proton chemical shifts of the dye has been proposed. The equilibrium constants of 1:1 and 1:2 complexes association of these molecules and the most probable structures of the complexes have been determined.

Acridines↗
PubMedDate not supplied

[Effect of temperature on the conformation of native DNA in aqueous solutions of various electrolytes].

Effect of the temperature on the conformation of the native DNA molecule in solution of different electrolytes (LiCl, NaCl, KCl, CsCl, Gu-HCl) at ionic strengths mu = 5; 0.1; 0.01; 0.005 and temperatures ranging from 10 to 40 degrees C were studied by the methods of flow birefringence and viscometry. The experiments showed that the value of intrinsic viscosity [eta] of DNA increases at increase of temperatures in solutions of all the chlorides studied, excluding guanidine. The effect of temperature on the value of [eta] doesn't depend on the type of the cation at a fixed value of mu and is elevated when mu decreases. The observed alterations of the value of [eta] for DNA in water-salt solutions at different temperatures can be explained by an increase in the hydration of the alkaline ions at temperature increase. The experiments showed the specificity of the effect of different ions on the dimensions of the DNA molecule in solution. The data on optical anisotropy of the DNA molecule testify, that the thermodynamic rigidity of the latter doesn't depend on the temperature of solutions of different electrolytes in the temperature range studied.

Animals↗
PubMedDate not supplied

[Conformation of the DNA molecule in alcohol-water solvents].

The influence of different alcohol-water solvents on the conformation of the native DNA molecule has been studied by the methods of flow birefringence and viscometry. The experiments have shown, that a certain content of the organic component induces a cooperative transition in the tertiary structure of the DNA molecule. The conformational transitions in the tertiary structure of DNA have been observed at low alcohol concentrations, corresponding to the desruption of the ordered spatial water structure and are caused by the alteration of the intermolecular interactions between the DNA and solvent molecules. The alcohol concentrations, corresponding to the observed transition, as well, as relative decrease of the intrinsic viscosity of DNA, depend on the chain length and branching of the hydrocarbon portion of the alcohols. The data on the optical anisotropy of the DNA molecule testify that the secondary structure of the latter doesn't change in a wide range of the alcohol concentrations.

Alcohols↗
PubMedDate not supplied

[Comparative study of DNA interactions with daunomycin and proflavine in a solution].

The comparative investigations of DNA complexes with daunomycin and proflavine were proceeded by the technique of spectrophotometry, viscometry and flow birefringence for two ionic strengths of environment (mu). According to the spectrophotometry data there is an unique type of ligand binding with DNA for mu = 0.1. The intrinsic viscosity and optical anisotropy of DNA-daunomycin complex increase nonlinearly together with its equilibrium rigidity as the amount of the binding ligand (r) rises, contrary to the behaviour of the same characteristics of DNA-proflavine complexes. The discussion of the experimental data within a scope of different models of binding reveals the best agreement with the intercalation model. Evaluation of the angels between the orientation planes of chromophore and aminoglucose residue of a daunomycin molecule and the axis of DNA double-helix was performed. Apart from intercalation there is a process of external binding of daunomycin with DNA in the low ionic strength (mu = 0.001) solutions which arises mainly at higher values of r. This type of binding weakens the long-range electrostatic interactions (and also to a certain extent the short-range ones) in DNA chain that determine the behaviour of the parameters under study.

Acridines↗
PubMedDate not supplied

[Self-association of deoxytetraribonucleoside triphosphates d(TpGpCpA) in an aqueous solution by 1H NMR spectroscopy].

Self-association of deoxytetraribonucleoside triphosphate 5'-d(TpGpCpA) molecules in aqueous solution has been studied by one-dimensional and two-dimensional 1H-NMR spectroscopy (500 MHz). Two-dimensional homonuclear PMR spectroscopy (2D-COSY and 2D-NOESY) was used for complete assignments of tetranucleotide proton signals. Concentration and temperature dependences of d(TpGpCpA) proton chemical shifts have been measured. Experimental results have been analyzed using dimer model of molecules association. Equilibrium association constant, values of limiting chemical shifts of tetranucleotide protons in the associate and thermodynamic parameters delta H and delta S of the association reaction have been determined. Comparative analysis of self-association characteristics for d(TpGpCpA) and its isomeric deoxytetranucleotide d(ApGpCpT) has been made.

Base Sequence↗
PubMedDate not supplied

[Study of the self-association of deoxytetraribonucleoside triphosphate molecules d(ApGpCpT) in aqueous solution by one-dimensional and two- dimensional (1)H NMR spectroscopy].

Equilibrium behaviour of self-complimentary deoxytetranucleotides d(ApGpCpT) in D2O solution has been studied by the method of proton magnetic resonance spectroscopy (500 MHz). Complete assignments of the d(ApGpCpT) protons were obtained from both two-dimensional homonuclear COSY- and NOESY-experiments. Concentration and temperature dependences of tetranucleotide proton chemical shifts have been investigated. The equilibrium association constants and thermodynamical parameters of self-association of the molecules have been calculated using theoretical models and regression equations based on experimental results.

Magnetic Resonance Spectroscopy↗
PubMedDate not supplied

[Study of complex formation of ethidium bromide with the self-complementary deoxytetranucleotide 5'-d(ApGpCpT) by unidimensional and two- dimensional 1H NMR spectroscopy].

Complex formation of ethidium bromide (3,8-diamino-6-phenyl-5-ethyl-phenanthridine) with the self-complementary desoxytetraribonucleosidetriphosphate d(ApGpCpT) was studied in aqueous solution by uni- and two-dimensional 1H NMR spectroscopy (500 and 600 MHz). The concentration dependence of the chemical shifts of protons of the complex at a fixed temperature (T = 308 K) were measured. The schemes of complexing of the dye with the tetranucleotide which take into account eventual molecular associates in solution are discussed. Equilibrium constants of the reactions and the limiting values for the chemical shifts of the protons of ethidium bromide incorporating into the complex were calculated. Relative contents of different complex types were analyzed. The relationship between the dynamic equilibrium and dye/tetranucleotide concentration ratio was examined. The conclusion is made that, as with the complex of proflavine with the d(AGCT) examined earlier, ethidium bromide is intercalated essentially into the G-C site of the tetranucleotide being in the duplex form. The difference in intercalation between ethidium bromide and proflavine lies in the fact that ethidium bromide incorporate on the side of the narrow groove, whereas proflavine is built in on the side of the large groove. Based on the calculated values of the induced chemical shift of ethidium bromide protons and 2-d NOE spectal data, an adequate model (1:2) of the complex of the dye with tetranucleotide in solution was constructed.

Ethidium↗