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Dive into the research topics where Marine A. Parsadanyan is active.

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Featured researches published by Marine A. Parsadanyan.


Journal of Biomolecular Structure & Dynamics | 2005

Complex-formation of Ethidium Bromide with poly[d(A-T)].poly[d(A-T)].

Poghos O. Vardevanyan; Ara P. Antonyan; Marine A. Parsadanyan; Hayk G. Davtyan; Zaruhi R. Boyajyan; Armen T. Karapetian

Abstract The interaction of Ethidium Bromide (EtBr) with double-stranded (ds-) and single-stranded (ss-) poly[d(A-T)] was studied in different ionic strengths solutions. Optical spectroscopy and Scatchard analysis results indicate that the ligand interacts to both helix and coiled structures of the polynucleotide by “strong” and “weak” binding modes. The association parameters (binding constant—K—and the number of nucleotides corresponding to a binding site—n) of the strong type of interaction were found to be independent of Na+ concentration. Weak interaction occurs at low ionic strength and/or high EtBr concentration. Estimated binding parameters of EtBr with ss- and ds-polynucleotide are in good agreement with those for EtBr-B-DNA complexes. Data obtained provided an evidence for a stacking interaction of EtBr with single stranded poly[d(A-T)].


Journal of the Brazilian Chemical Society | 2012

The influence of GC/AT composition on intercalating and semi-intercalating binding of ethidium bromide to DNA

Poghos O. Vardevanyan; Ara P. Antonyan; Marine A. Parsadanyan; Mariam A. Shahinyan; Lilit A. Hambardzumyan; Margarita A. Torosyan; Armen T. Karapetian

The binding parameters of ethidium bromide (EtBr) with DNA of various GC/AT ratios were determined using absorption and fluorescence spectroscopy. Our experimental data clearly demonstrate the co-existence of fluorescing and non-fluorescing types of “strong” binding at low concentration of EtBr. The fluorescent complex corresponds to the ordinary intercalative model. The non-fluorescent complex is referred to semi-intercalative binding of EtBr. The binding constant (K) and the number of base pairs corresponding to a binding site (n) of the fluorescent (K f and n f ) and non-fluorescent (K nf, nnf) types of interactions were determined. The average size of binding site (n) is equal to 1.5 bp (absorption spectroscopy), and nf ca. 2 bp (fluorescence spectroscopy). It was shown that nnf is dependent on GC-content and total n is independent of it.


Modern Physics Letters B | 2014

Analysis of experimental binding curves of EtBr with single- and double-stranded DNA at small fillings

Poghos O. Vardevanyan; Valeri B. Arakelyan; Marine A. Parsadanyan; Ara P. Antonyan; Gohar G. Hovhannisyan; Mariam A. Shahinyan

In this paper, a method that allows to analyze the binding curves of ligand (EtBr) with single-stranded (ss) and double-stranded (ds) DNA, when there are at least two modes of ligand binding to DNA at small fillings has been proposed. The obtained experimental binding curves for EtBr–ssDNA and EtBr–dsDNA have two clearly expressed linear regions. These curves were analyzed by two modes: Experimental points on linear regions were described by two different lines and all experimental points were described by single curve. It was revealed that the description by single curve permits obtaining more precise data of binding parameters (i.e. binding constant and number of base pairs that bind one ligand molecule). Moreover, the proposed method permits determining the value of proportion of binding sites of each binding mode.


Journal of Biomolecular Structure & Dynamics | 2006

Kinetics of ligand binding to nucleic acids

Valeri B. Arakelyan; Babayan Sy; Tairyan Vi; Arakelyan Av; Marine A. Parsadanyan; Poghos O. Vardevanyan

Abstract Ligand binding to nucleic acids (NA) is considered as a stationaiy Markov process. It is shown that the probabilistic description of ligand-NA binding allows one to describe not only the kinetics of the change of number of bound ligands at arbitrary fillings but also to calculate stationaiy values of the number of bound ligands and its dispersion. The general analysis of absoiption isotherms and kinetics of ligand binding to NA make it possible to determine of rate constants of ligand-NA complex formation and dissociation.


Journal of Biomolecular Structure & Dynamics | 2016

Joint interaction of ethidium bromide and methylene blue with DNA. The effect of ionic strength on binding thermodynamic parameters

Poghos O. Vardevanyan; Ara P. Antonyan; Marine A. Parsadanyan; Margarita A. Torosyan; Armen T. Karapetian

Large amount of data of experimental and theoretical studies have shown that ethidium bromide (EtBr) and methylene blue (MB) may bind to nucleic acids via three modes: intercalation between two adjacent base pairs, insertion into the plane between neighboring bases in the same strand (semi-intercalation), and outside binding with negatively charged backbone phosphate groups. The aim of the given research is to examine the behavior of these two ligands at both separate and joint DNA binding. The obtained experimental data show that the effect of simultaneous binding of EtBr and MB on double-stranded DNA has a non-additive effect of separate binding. The analyses of the melting thermodynamic parameters of DNA complexes with two bound ligands suggest competitive mechanism of interaction.


Journal of Biomolecular Structure & Dynamics | 2014

Kinetics of adsorption of extended ligands on DNA at small fillings.

Valeri B. Arakelyan; Poghos O. Vardevanyan; Zaven E. Navoyan; Marine A. Parsadanyan; Gohar G. Hovhannesyan; Armen T. Karapetian

In the present work, the adsorption kinetics of extended ligands on DNA duplexes at small fillings when molecules of DNA duplexes are on the underlayer within diffusion layer has been investigated. Both diffusion of ligands in solution (diffusion stage) and adsorption of ligands (kinetic stage) are taken into consideration at adsorption of ligands on DNA duplexes. Nonlinear system of differential equations describing adsorption of ligands where not only diffusion stage but also kinetic stage is taken into account, is obtained, moreover the equations allow localizing duplexes in arbitrary place within diffusion layer. Numeric solution of the equations makes possible to investigate the filling kinetics of DNA duplexes by ligands depending on parameters controlling adsorption process. It has been shown that depending on relation between adsorption parameters different kinetic regimes of adsorption – kinetic, complex, and diffusion regimes may be realized.


Russian Journal of Plant Physiology | 2002

RNA Export and Electrokinetic Potential of Nuclei in Germinating Embryos of Cereal Crops

L. A. Minasbekyan; Marine A. Parsadanyan; S. A. Gonyan; Poghos O. Vardevanyan

The changes in the contents of major components in the nuclei and nuclear membranes during germination of cereal crop embryos were studied. Treatment with RNase of intact nuclei from both dry and germinating embryos changed the electrokinetic potential (EKP) of the nuclear surface. The interrelations between an increased RNA export from isolated nuclei and increased EKP during germination were shown. The conclusion was drawn that the rate of RNA export from the nuclei affected substantially the EKP value, which opens new possibilities for studying physicochemical properties of the nuclear membrane in relation to the functional state of the genetic apparatus and the physiological state of the plant cell.


Journal of Contemporary Physics-armenian Academy of Sciences | 2015

Absorption and fluorescence spectra of polynucleotide complexes with ethidium bromide

Poghos O. Vardevanyan; Ara P. Antonyan; Marine A. Parsadanyan; Mikayel V. Minasyants

We study the ethidium bromide (EtBr) interaction with the poly(dA)-poly(dT) and poly[d(A-T)]-poly[d(A-T)] polynucleotides at 0.02 M ionic strength of solution and pH = 7.2. It was revealed that the EtBr binds to the poly[d(A-T)]-poly[d(A-T)] by three modes: the intercalation, semiintercalation and weak (electrostatic), while with the poly(dA)-poly(dT) by two modes: the intercalation and semi-intercalation. Moreover, EtBr binds to the poly(dA)-poly(dT) cooperatively and to the poly[d(A-T)]-poly[d(A-T)] non-cooperatively.


International Journal of Spectroscopy | 2015

Behavior of Ethidium Bromide-Hoechst 33258-DNA and Ethidium Bromide-Methylene Blue-DNA Triple Systems by means of UV Melting

Poghos O. Vardevanyan; Ara P. Antonyan; Marine A. Parsadanyan; Mariam A. Shahinyan; Gayane A. Melkonyan

The study of EtBr and H33258 interaction as well as EtBr and MB interaction with DNA has been carried out. It was revealed that, at joint interaction, the effect of two ligands on the change of melting thermodynamic parameters of EtBr-DNA-H33258 or EtBr-DNA-MB complexes is not an addition of separate interaction influences. It was shown that, at joint, binding of EtBr and MB with DNA competition occurs, while in the case of EtBr and H33258, the mutual strengthening of stabilizing effect of each of them on DNA double-stranded structure mainly takes place.


Biophysical Reviews and Letters | 2014

Ethidium Bromide Interaction with Poly(G)

Poghos H. Vardevanyan; Marine A. Parsadanyan; Mikayel V. Minasyants

In current work we investigate the interaction between polyguanylic acid and Ethidium Bromide (EtBr) and the changes of thermodynamic parameters due to those interactions by spectrophotometric methods. From the binding isotherms, binding constants were calculated for three different temperatures and the changes of Gibbs free energy, entropy and enthalpy for complex-formation were determined. Complex-formation with four-stranded poly(G) structure needs less conformational changes in contrast with poly(G)poly(C), and due to that, EtBr binds with 5 and not 4 nucleotides. Obtained results confirm the concept that polyguanylic acids may form four-stranded complex structures with intercalating ligand EtBr in the aqueous solution.

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H.G. Davtyan

Yerevan State University

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