Effect of competing self-structure on triplex formation with purine-rich oligodeoxynucleotides containing GA repeats.

摘要: Abstract Competition between triplex formation with double-stranded DNA and oligonucleotide self-association was investigated in 23mer GA GT oligonucleotides containing d(GA)5 or d(GT)5 repeats. Whereas diminished when temperature increased from 4 to 37 degrees C, enhanced within the same range due presence of competing intermolecular self-structure. This self-structure determined be a homoduplex stabilized by internal UV spectroscopy these homoduplexes demonstrated single sharp transition rapid kinetics (Tm = 38.5-43.5 C over strand concentrations 0.5-4 microM, respectively, enthalpy, delta H -89 +/- 7 kcal/mol) 10 mM MgCl2, 100 NaCl, pH 7.0. Homoduplex strongly multivalent cations (spermine > Mg2+ Ca2+) destabilized low monovalent (K+ Li+ Na+) divalent cations. However, unlike oligonucleotide-containing triplexes, formed even absence cations, only moderate (Li+ Na+ K+). Through development multiple equilibrium states resulting depletion free oligonucleotide, it found that could decrease under variety experimental conditions.