THE ISOLATION, IDENTIFICATION, AND PROPERTIES OF DINUCLEOTIDES FROM ALKALI HYDROLYZATES OF RIBONUCLEIC ACIDS

Abstract

The isolation, identification, and properties of dinucleotides from alkali hydrolyzates of RNA are described. Preparative methods for obtaining the alkali-labile dinucleotides which were found in our 18-hour hydrolyzates of RNA in 1 M potassium hydroxide are described, and it is noted that all of them (ApAp, ApGp, ApUp, GpAp, and GpCp) are not susceptible to pancreatic ribonuclease at the concentrations of the enzyme which are customarily employed for hydrolytic degradations. It has been found, however, that two of these dinucleotides (ApAp and ApUp) are susceptible to pancreatic ribonuclease at concentrations of the enzyme which are about five thousand times greater than those customarily employed. The rate constants of first order hydrolysis in alkali of ApAp, ApGp, ApUp, GpAp, and GpCp are found to be correspondingly lower than the rate constants for two dinucleotides which were not found in our 18-hour hydrolyzates, and which are susceptible to pancreatic ribonuclease. Furthermore, it is reported that the eight possible diribonucleotides which are not susceptible to pancreatic ribonuclease (ApAp, ApGp, ApCp, ApUp, GpGp, GpAp, GpCp, and GpUp) are found in roughly equivalent amounts in a 2-hour alkali hydrolyzate of a preparation of yeast RNA, and account for 80–90% of the dinucleotides present.In addition to the alkali-labile dinucleotides found in alkali hydrolyzates of RNA, the isolation and preliminary characterization of five alkali-stable compounds are reported.