Open AccessAssociation of Nucleic‐Acid Bases in Aqueous Solution: a Solvent Partition Study
Author(s) -
Gratzer W. B.
Publication year - 1969
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1969.tb00671.x
Subject(s) - chemistry , pyrimidine , cytosine , nucleotide , nucleic acid , uracil , aqueous solution , guanine , purine , solvent , dna , nucleobase , organic chemistry , stereochemistry , biochemistry , gene , enzyme
A method is described for determining homologous and heterologous interactions between nucleic acid bases. Derivatives soluble in both water and an immiscible solvent, such as chloroform, are partitioned between the solvent and solutions of mononucleotides, at pH corresponding to substantial ionization of the secondary phosphate, so that self‐association of the nucleotide is minimised. The concentration of the base derivative is kept 2–3 orders of magnitude below that of the nucleotide, the partition ratio being determined spectrophotometrically by sampling the non‐aqueous phase. Adenine and uracil, but not so far guanine and cytosine, derivatives with the requisite solubility characteristics have been found. 9‐Ethyladenine and 1‐cyclohexyluracil were partitioned against a series of nucleotide solutions and association constants were determined and were found invariant with nucleotide concentration. Purine‐purine associations are much the strongest, followed by purine‐pyrimidine; the pyrimidine‐pyrimidine associations which have been investigated are vanishingly small. Published data, based on other methods, are largely confined to self‐associations; where comparison with results on uncharged derivatives, principally the nucleosides, is possible, agreement is satisfactory.