INTERACTION OF NUCLEIC ACIDS, I. PHYSICAL BINDING OF THYMINE, ADENINE, STEROIDS, AND AROMATIC HYDROCARBONS TO NUCLEIC ACIDS

Abstract

The affinity constants (nk), where n is the number of the binding sites and k is the average association constant of each site, between certain compounds and nucleic acids have been measured by equilibrium dialysis at 5[degree]C in buffered solutions containing 0.5 [image] salt. The order of the increasing affinity constants of these compounds to the nucleic acids was found to be: thymine << adenine, caffeine < naphthalene< diethylstilbesteroK estradiol-[beta]-17< testosterone < phenanthrene. The affinity constants of the nucleic acids in coil form was found to be much higher than those of nucleic acids in helical form. Desoxyribonucleic acid has a two order of magnitude higher affinity constant than ribonucleic acid. Nucleic acids tested were native and heat-denatured thymus DNA, helical poly A and coil poly A, poly U, ribosomal RNA, as well as yeast sRNA.