2026-05-30T15:35:47Zhttps://riubu.ubu.es/oai/request

oai:riubu.ubu.es:10259/47462022-04-29T12:02:48Zcom_10259_4365com_10259_5086com_10259_2604com_10259_4883col_10259_4366col_10259_4884

2019-03-01T03:45:06Z urn:hdl:10259/4746 Kinetic evidence for interaction of TMPyP4 with two different G-quadruplex conformations of human telomeric DNA Pérez Arnáiz, Cristina Busto Vázquez, Natalia Santolaya, Javier Leal Villalba, José María Barone, Giampaolo García Ruiz, Begoña Tel22 conformations TMPyP4 Fast reactions Molecular dynamics Background: Stabilization of G-quadruplex helices by small ligands has attracted growing attention because they inhibit the activity of the enzyme telomerase, which is overexpressed in> 80% cancer cells. TMPyP4, one of the most studied G-quadruplex ligands, is used as a model to show that the ligands can exhibit different binding features with different conformations of a human telomeric specific sequence. Methods: UV–Vis, FRET melting Assay, Isothermal Titration Calorimetry, Time-resolved Fluorescence lifetime, T-Jump and Molecular Dynamics. Results: TMPyP4 yields two different complexes with two Tel22 telomeric conformations in the presence of Na+ or K+. T-Jump kinetic experiments show that the rates of formation and dissociation of these complexes in the ms time scale differ by one order of magnitude. MD simulations reveal that, in K+ buffer, “hybrid 1” conformation yields kinetic constants on interaction with TMPyP4 one order lower than “hybrid 2”. The binding involves π–π stacking with external loop bases. Conclusions: For the first time we show that for a particular buffer TMPyP4 interacts in a kinetically different way with the two Tel22 conformations even if the complexes formed are thermodynamically indistinguishable. General significance: G-quadruplexes, endowed with technological applications and potential impact on regulation mechanisms, define a new research field. The possibility of building different conformations from same sequence is a complex issue that confers G-quadruplexes very interesting features. The obtaining of reliable kinetic data constitutes an efficient tool to determine reaction mechanisms between conformations and small molecules. 2018-03-08T09:23:37Z 2019-03-01T03:45:06Z 2018-03 info:eu-repo/semantics/article 0304-4165 http://hdl.handle.net/10259/4746 10.1016/j.bbagen.2017.10.020 eng Biochimica et biophysica acta (BBA) - general subjects. 2018, V. 1862, n. 3, p. 522-531 https://doi.org/10.1016/j.bbagen.2017.10.020 info:eu-repo/grantAgreement/“la Caixa” Foundation/OSLC-2012-007 info:eu-repo/grantAgreement/MINECO/CTQ2014-58812-C2-2-R info:eu-repo/grantAgreement/JCyL/BU042U16 http://creativecommons.org/licenses/by-nc-nd/4.0/ info:eu-repo/semantics/openAccess Attribution-NonCommercial-NoDerivatives 4.0 International Elsevier