Structure, internal motions and association-dissociation kinetics of the i-motif dimer of d(5mCCTCACTCC).

ABSTRACT: At slightly acidic pH, the association of two d(5mCCTCACTCC) strands results in the formation of an i-motif dimer. Using NMR methods, we investigated the structure of [d(5mCCTCACTCC)]2, the internal motion of the base pairs stacked in the i-motif core, the dimer formation and dissociation kinetics versus pH. The excellent resolution of the 1H and 31P spectra provided the determination of dihedral angles, which together with a large set of distance restraints, improve substantially the definition of the sugar-phosphate backbone by comparison with previous NMR studies of i-motif structures. [d(5mCCTCACTCC)]2 is built by intercalation of two symmetrical hairpins held together by six symmetrical C*C+ pairs and by pair T7*T7. The hairpin loops that are formed by a single residue, A5, cross the

SUBMITTER: Canalia M 

PROVIDER: S-EPMC1243796 | biostudies-literature | 2005

REPOSITORIES: biostudies-literature