Besik I. Kankia

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It has been shown that the DNA aptamer d(G(2)T(2)G(2)TGTG(2)T(2)G(2)) adopts an intramolecular G-quadruplex structure in the presence of K+. Its affinity for trombin has been associated with the inhibition of thrombin-catalyzed fibrin clot formation. In this work, we used a combination of spectroscopy, calorimetry, density, and ultrasound techniques to(More)
During minus-strand DNA synthesis, RNase H degrades viral RNA sequences, generating potential plus-strand DNA primers. However, selection of the 3' polypurine tract (PPT) as the exclusive primer is required for formation of viral DNA with the correct 5'-end and for subsequent integration. Here we show a new function for the nucleic acid chaperone activity(More)
The interaction of hexamminecobalt(III), Co(NH(3))(6)(3+), with 160 and 3000-8000 bp length calf thymus DNA has been investigated by circular dichroism, acoustic and densimetric techniques. The acoustic titration curves of 160 bp DNA revealed three stages of interaction: (i) Co(NH(3))(6)(3+) binding up to the molar ratio [Co(NH(3))(6)(3+)]/[P] = 0.25, prior(More)
The human immunodeficiency virus type 1 nucleocapsid protein (NC) is a nucleic acid chaperone that catalyzes the rearrangement of nucleic acids into their thermodynamically most stable structures. In the present study, a combination of optical and thermodynamic techniques were used to characterize the influence of NC on the secondary structure, thermal(More)
The introduction of cationic 5-(omega-aminoalkyl)-2'-deoxypyrimidines into duplex DNA has been shown to induce DNA bending. In order to understand the energetic and hydration contributions for the incorporation of a cationic side chain in DNA a combination of spectroscopy, calorimetry and density techniques were used. Specifically, the temperature unfolding(More)
Quadruplexes are involved in the regulation of gene expression and are part of telomeres at the ends of chromosomes. In addition, they are useful in therapeutic and biotechnological applications, including nucleic acid diagnostics. In the presence of K(+) ions, two 15-mer sequences d(GGTTGGTGTGGTTGG) (thrombin binding aptamer) and d(GGGTGGGTGGGTGGG) (G3T)(More)
We previously developed a method, known as quadruplex priming amplification (QPA), which permits isothermal amplification of DNA. The assay is based on a DNA quadruplex formed by the GGGTGGGTGGGTGGG (G3T) sequence. G3T has three unique properties that are fundamental for QPA; (i) G3T forms a quadruplex with significantly more favorable thermodynamics than(More)
We have developed a new method, quadruplex priming amplification, to greatly simplify nucleic acid amplification and real-time quantification assays. The method relies on specifically designed guanine-rich primers, which after polymerase elongation are capable of spontaneous dissociation from target sites and forming DNA quadruplex. The quadruplex is(More)
We report on the physicochemical effects resulting from incorporating a 5-(3-aminopropyl) side chain onto a 2'-deoxyuridine (dU) residue in a short DNA hairpin. A combination of spectroscopy, calorimetry, density and ultrasound techniques were used to investigate both the helix-coil transition of a set of hairpins with the following sequence:(More)
The binding of Mg(2+) to single-stranded ribo- and deoxy-polynucleotides, poly(rA), poly(rU), poly(dA) and poly(dT), has been investigated in dilute aqueous solutions at pH 7.5 and 20 degrees C. A combination of ultrasound velocimetry, density, UV and CD spectroscopy have been employed to study hydration and spectral effects of Mg(2+) binding to the(More)