Louis Katz, Sheldon Penman
1966
Citations
1
Influential Citations
197
Citations
Quality indicators
Journal
Journal of molecular biology
Abstract
The interactions of purines and pyrimidines in solution have been studied by measuring their proton magnetic resonance spectra. In dimethyl sulfoxide, a solvent with no exchangeable protons, a hydrogen-bonding interaction between the complementary bases guanine and cytosine is evident in the large down-field shifts of the donor protons. No association is seen for adenine—uracil combinations in this solvent, apparently because of the competition of the capability of hydrogen-bond acceptance of the solvent with that of the bases. In the relatively non-hydrogen bonding solvent chloroform, intermolecular base association between soluble adenine and uracil derivatives is clearly observed. Chemical shifts of the donor protons as a function of varying relative nucleoside concentrations indicates a one-to-one association between guanosine and cytidine. The behavior of the adenine—uracil mixtures indicates a higher-order interaction. By using a mixed solvent system consisting of one hydrogen bond-accepting component and another component which is inert, it is possible to obtain solutions of and to measure the interactions between various nucleosides. In this mixed solvent system a striking specificity of interaction is evident. Guanosine interacts with cytidine strongly and, except for a weak self-association, interacts with no other nucleoside. Uridine associates with adenosine and shows no other interaction. In pure dimethyl sulfoxide, the only interaction of cytidine is with guanosine.