Structure, kinetics and thermodynamics of DNA hairpin fragments in solution.
The hairpin-to-coil equilibrium of the hexadecadeoxynucleotide d(ATCCTATTTTTAGGAT) was extensively studied by means of NMR, T-jump and UV. The thermodynamic and kinetic parameters for this equilibrium were determined, yielding a consistent picture of the dynamical behavior of this hairpin structure, which is shown to be a clear example of a situation in which the linebroadening of the imino proton resonances is not determined by the lifetime of the double helix. A comparative study of the homologous hairpins in which the size of the loop was elongated from 4 to 7 thymidine residues shows a monotonous decrease in Tm for the hairpin-to-coil transitions. This finding is in contrast with the view that the stability of hairpins reaches a maximum with a loop size of 6-7 residues. The NMR results indicate that the accessibility of the thymine bases in the loop towards solvent molecules or complementary nucleotides greatly depends on the size of the loop.
D001483:Base Sequence; D004247:DNA; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D009690:Nucleic Acid Conformation; D011089:Polydeoxyribonucleotides; D012996:Solutions; D013816:Thermodynamics
D011089:Polydeoxyribonucleotides; D012996:Solutions; D004247:DNA