Experimental studies of molecular interactions between nitrogen bases of nucleic acids

Abstract

SynopsisNew experimental results concerning molecular interactions between the nitrogen bases of nucleic acids in the crystalline phase and in uucuo are reported. The temperature dependence of the evaporation rate is measured for solid species. The sensitivity of conventional methods of sublimation heat measurements was improved essentially using a quartz resonator serving as a precise sensor of evaporation rate. Sublimation heats were found for both canonical bases and a number of their derivatives. The in uucuo formation of base associates interacting through hydrogen bonds was observed with a field mass spectrometer. The dimer formation enthalpies, which are indicative of a stronger attraction in complementary pairs compared with noncomplementary ones, were derived from the temperature dependence of ionic currents. Hydrogen-bound complexes of more intricate associates (base trimers and aqueous molecule associates) were studied. The energy gain in the formation of trimers of identical molecules was shown to be larger (per base molecule) than that for dimers.

Thermodynamics of G⋅A mispairs in DNA: Continuum electrostatic model

“…with the experimental data for the canonical pairs shows very good agreement. [32] with correction proposed in [33].…”

(G–H) • –C and G–(C–H) • radicals derived from the guanine·cytosine base pair cause DNA subunit lesions

“…Complexation energies upon base pair formation have also been computed for both of the DNA base pairs (26)(27)(28)(29)(30)(31), and electron affinities of the single bases (32) and base pairs have been evaluated (27,33).…”

Molecular mechanism of base pairing infidelity during DNA duplication upon one-electron oxidation

“…The calculated hydrogen bonding energy of the G (-H) • -A base pair is -13.6 kcal/mol, as shown in Figure 4. This binding is somewhat stronger than that for the natural A-T pairing (-13.0 kcal/mol) [24,25,29,35] .…”

“…This lies between the BPE's of the adenine-thymine base pair (A-T) at -13.0 kcal/mol and that of G-C at -21.0 kcal/mol [24,25] .…”

“…•+ -C is increased to -40.9 kcal/mol compared to -21.0 kcal/mol of its parent pair, inhibiting the frequency of the breathing motions of the base pair [24,29,30] . Second, when duplication of DNA occurs, the DNA strand is untwisted and the hydrogen bonds between the bases are broken to allow duplication of the strand.…”