title: Hairpin and duplex formation of the DNA octamer d(m5C-G-m5C-G-T-G-m5C-G) in solution. An NMR study.
abstract: The partly self-complementary DNA octamer d(m5C-G-m5C-G-T-G-m5C-G) was investigated by NMR spectroscopy in solution. It is demonstrated that this peculiar DNA fragment, under suitable conditions of concentration, salt and temperature, exclusively prefers to adopt a monomeric hairpin form with a stem of three Watson-Crick type base pairs and a loop of two residues. At high single strand concentration (8 mM DNA) and low temperature (i.e. below 295 K) the hairpin occurs in slow equilibrium with a B-dimer structure. At high ionic strength (greater than or equal to 100 mM Na+) and/or in the presence of methanol a third species appears, which is assigned to a Z-like dimer. In the B form, as well as in the Z dimer, the two central base pairs form G.T wobble pairs with the bases as major tautomers.
mesh_terms: D001483:Base Sequence; D004247:DNA; D009682:Magnetic Resonance Spectroscopy; D000432:Methanol / Q000494:pharmacology; D009690:Nucleic Acid Conformation; D009994:Osmolar Concentration; D013696:Temperature
chemical_list: D004247:DNA; D000432:Methanol