Comparison of the kinetics of ribooligonucleotide, deoxyribooligonucleotide, and hybrid oligonucleotide double-strand formation by temperature-jump kinetics.

The kinetics of double-strand formation were measured by using temperature-jump kinetic techniques for the DNA oligonucleotides dCA5G + dCT5G, the analogous RNA oligonucleotides rCA5G + rCU5G, and the hybrid rCA5G + dCT5G. The DNA oligonucleotides have a faster rate of recombination and a slower rate of dissociation at 12.0 degrees C than the RNA oligonucleotides; the hybrid has about the same recombination rate and a slightly faster dissociation rate than the RNA oligonucleotides. The activation energies for recombination for the DNA and RNA oligonucleotides are both near 0 kcal/mol. The difference in dissociation and recombination activation energies is consistent with the thermodynamic results obtained earlier. The relaxation process is composed of two exponential components for the RNA and hybrid oligonucleotides at temperatures of 12.0 degrees C and lower. One exponential component is observed for these oligonucleotides above 12.0 degrees C and for the DNA oligonucleotides at all temperatures.