Raman spectral studies of nucleic acids. 18. Kinetics of hydrogen-deuterium exchange in guanosine 5'-monophosphate and guanosine 3':5'-monophosphate determined by laser-Raman spectroscopy

Abstract

Pseudo-first-order rate constants governing the deuterium exchange of 8-CH groups in guanosine 5'-monophosphate (5'-rGMP) and guanosine 3':5'-monophosphate (cGMP) were determined as a function of temperature in the range 30-80 degrees C by means of laser-Raman spectroscopy. For each guanine nucleotide the logarithm of the rate constant exhibits a strictly linear dependence on reciprocal temperature: i.e., k psi = Ae-Ea/RT with A = 8.84 X 10(14) h-1 and Ea = 24.6 kcal/mol for 5'-rGMP and A = 3.33 X 10(13) h-1 and Ea = 22.2 kcal/mol for cGMP. Exchange of the 8-CH groups in guanine nucleotides is generally 2-3 times more rapid than in adenine nucleotides [cf. g. j. thomas, Jr., & J. Livramento (1975) Biochemistry 14, 5210-5218]. As in the case of adenine nucleotides, cyclic and 5' nucleotides of guanine exchange at markedly different rates at lower temperatures, with exchange in the cyclic nucleotide being the more facile. Each of the guanine nucleotides was prepared in four different isotopic modifications for Raman spectral analysis. The Raman frequency shifts resulting from the various isotopic substitutions have been tabulated, and assignments have been given for most of the observed vibrational frequencies.

Interaction of Z form poly(dG-dC). poly(dG-dC) with divalent metal ions: localization of the binding sites by I.R. spectroscopy

“…thing involving the N7 motion is similarly shifted to 1464 cm 1 by selective deuteration of the C8 site (25). Thus the modifications of the 1467 cm 1 absorption of the IR spectrum of poly(dD8G-dC).poly(dD8G-dC) will reflect specific interactions with the N7 of guanines.…”

“…Biochemicals. Specific deuteration of the guanines was obtained by incubation in D20 at 80°C for 3 hours (24)(25). Samples (Fig.…”

Magnesium – nucleotide interaction. Synthesis, structure, 1H, 13C nuclear magnetic resonance and Fourier transform infrared studies of Mg-inosine-5′-monophosphate complexes

“…1) as in the case of the Ni(IMP).5HI0 which contains no metal-sugar interaction. Other sugar-phosphate bands (27) in the region 900-600 cm-' also exhibited splitting and shifting as well as intensity changes ( Fig. 1 and Table 2) depending upon the nature of metalligand bonding (N7-, phosphate or sugar).…”

“…The symmetric and asymmetric stretching vibrations of the sugar OH, CH, and CH, groups in mononucleotides have been observed (1 8,19,27) in the region 3600-2700 cm-' overlapping with the NH, NH2 stretchings of the base moiety and the H,O of the metalhydrated water molecules. Other vibrational frequencies related to the ribose ring are also appearing as sharp and fine absorption bands in the region 1400-400 cm-' which are also obscured by the strong and broad absorption bands of the phosphate group and the base moiety.…”

The Synthesis of Deuterionucleosides

“…The pH-dependent kinetic studies of exchange process have also been performed 52,71,83,[85][86][87][88] . It has been found, that within a certain pH range, the structure of the purine could be unchanged (neither protonated nor deprotonated).…”