The frequencies of certain sequences of nucleotides in deoxyribonucleic acid

Publisher Website
Google Scholar
Abstract
A number of aromatic amines induce the release of inorganic orthophosphate from deoxyribonucleic acid (DNA) in aqueous 66% (volume/volume) formic acid at 30[degree]. The reaction with diphenylamine, the most effective of the amines tested, has been studied in detail. The purines are first removed and then both phosphoester bonds attached to the exposed deoxyribose residues are broken. Phosphodiester groups joining 2 purine nucleoside residues are converted into inorganic phosphate. Sequences of pyrimidine nucleotides appear quantitatively as nucleoside 3[image], 5[image] -diphosphates and as di- and oligonucleotides with terminal phosphate groups at both ends. After enzymic removal of the terminal phosphate groups, many of the pyrimidine oligonucleotides can be separated by two-dimensional chromatography on paper, thus providing a simple method for the study of the frequencies of certain sequences of nucleotides. In calf-thymus DNA there is a slight bias in favor of 3 or more consecutive pyrimidine nucleotides. These amount to about 61% of the total pyrimidines instead of the 50% for a random arrangement. Evidence is given that runs of 4 and 5 thymine nucleotides with a purine nucleotide at each end occur in amounts which are somewhat similar to those of a random arrangement.