title: A circular dichroism study of the stability of guanine quadruplexes of thrombin DNA aptamers at presence of K+ and Na+ ions.
abstract: The effect of K+ and Na+ on the properties of DNA aptamers that selective binds to fibrinogen (FIBRI) and heparin (HEPA) exosites of human alpha-thrombin was studied by circular dichroism (CD). The complexes of FIBRI-K+ were slightly more stable than HEPA-K+. However, lower stability was observed for HEPA-K+ at presence of Na+ in comparison with FIBRI-K+. The analysis of CD melting curves suggests differences in thermal stability of both aptamers at presence of K+. The melting temperatures (Tm) and changes in van't Hoff enthalpy for HEPA-K+ complexes were lower in comparison with those for FIBRI-K+. With increasing HEPA concentration the Tm value increased, but Tm did not change with increasing FIBRI concentration. This suggests formation of HEPA aggregates, while FIBRI aptamers are in monomeric form.
authors.affiliation: Department of Nuclear Physics and Biophysics, Faculty of Mathematics, Physics and Informatics, Comenius University, 842 48 Bratislava, Slovakia.
authors.forename: Slavomíra
authors.initials: S
authors.lastname: Poniková
authors.forename: Marián
authors.initials: M
authors.lastname: Antalík
authors.forename: Tibor
authors.initials: T
authors.lastname: Hianik
mesh_terms: D052157:Aptamers, Nucleotide / Q000737:chemistry*; D002412:Cations / Q000737:chemistry; D002942:Circular Dichroism / Q000379:methods; D005340:Fibrinogen / Q000737:chemistry; D054856:G-Quadruplexes; D006493:Heparin / Q000737:chemistry; D006801:Humans; D011188:Potassium / Q000737:chemistry*; D012964:Sodium / Q000737:chemistry*; D013917:Thrombin / Q000737:chemistry*
chemical_list: D052157:Aptamers, Nucleotide; D002412:Cations; D005340:Fibrinogen; D006493:Heparin; D012964:Sodium; D013917:Thrombin; D011188:Potassium