title: Influence of pH, temperature and the cationic porphyrin TMPyP4 on the stability of the i-motif formed by the 5'-(C3TA2)4-3' sequence of the human telomere.
abstract: The influence of pH, temperature and the cationic porphyrin TMPyP4 on the conformational equilibria of the cytosine-rich strand of the human telomeric sequence 5'-(C(3)TA(2))(4)-3', as well as those of the sequence 5'-(C(3)TT(2))(4)-3', was studied. The presence of adenine bases at the loops causes the formation of two different intramolecular i-motif structures with a pH-transition midpoint around 4.6, which stability is lower than the i-motif formed by the sequence 5'-(C(3)TT(2))(4)-3'. The stoichiometries of the complexes formed by these i-motif structures with TMPyP4 are also influenced by the presence of adenine at the loops.
authors.affiliation: Solution Equilibria and Chemometrics group (Associate Unit UB-CSIC), Department of Analytical Chemistry, University of Barcelona, Barcelona, Spain.
authors.forename: Sergio
authors.initials: S
authors.lastname: Fernández
authors.forename: Ramon
authors.initials: R
authors.lastname: Eritja
authors.forename: Anna
authors.initials: A
authors.lastname: Aviñó
authors.forename: Joaquim
authors.initials: J
authors.lastname: Jaumot
authors.forename: Raimundo
authors.initials: R
authors.lastname: Gargallo
mesh_terms: D001483:Base Sequence; D002412:Cations; D006801:Humans; D006863:Hydrogen-Ion Concentration; D016018:Least-Squares Analysis; D015999:Multivariate Analysis; D059372:Nucleotide Motifs; D011166:Porphyrins / Q000737:chemistry*; D013057:Spectrum Analysis; D016615:Telomere / Q000737:chemistry* / Q000235:genetics*; D013696:Temperature
chemical_list: D002412:Cations; D011166:Porphyrins; C021096:tetra(4-N-methylpyridyl)porphine