Effect of methylation on the pyrimidine-pyrimidine stacking interaction studied by (1)H NMR chemical shift

Mutually induced proton chemical shift changes were measured for the mixed solutions of pyrimidine and its methylated forms in deuterium oxide at 35 degrees C. The chemical shift vs. concentration profiles were analyzed using a three-state decomposition model based on competitive self- and hetero-as...

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Bibliographic Details
Published inBiophysical chemistry Vol. 54; no. 1; pp. 67 - 73
Main Author Aradi, F
Format Journal Article
LanguageEnglish
Published Netherlands 01.03.1995
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Summary:Mutually induced proton chemical shift changes were measured for the mixed solutions of pyrimidine and its methylated forms in deuterium oxide at 35 degrees C. The chemical shift vs. concentration profiles were analyzed using a three-state decomposition model based on competitive self- and hetero-association dimer equilibria. The equilibrium constants show an increasing association tendency within the series pyrimidine-5-methyl-pyrimidine (0.23 +/- 0.02 M(-1)) < pyrimidine-4,6-dimethyl-pyrimidine (0.32 +/- 0.04 M(-1)) < 5-methyl-pyrimidine-4,6-dimethyl-pyrimidine (0.51 +/- 0.04 M(-1)). The upfield dimer shifts suggest an offset stacked geometry for the structure of associations between the parent molecule of the pyrimidine nucleobases and its methylated derivatives in aqueous solution.
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ISSN:0301-4622
1873-4200
DOI:10.1016/0301-4622(94)00115-Z