The purine and pyrimidine composition of yeast ribonucleic acid.

Various chromatographic, spectrophotometric, and ion exchange procedures have been used recently with somewhat varying results for the analysis of yeast ribonucleic acid for its constituent purine and pyrimidine components (l-5). The reasons for the variations may be due in part to differences in the samples analyzed and in part to deficiencies in the methods used. Some of these deficiencies have been discussed in the preceding publication (6), in which certain improvements in the spectrophotometric procedures for the determination of the purine and pyrimidine components. are described. The present paper is concerned with the results found when the latter method of analysis was applied to a commercial sample of yeast sodium ribonucleate,. to a carefully prepared sample of ribonucleic acid from bakers’ yeast, and to a commercial sample of the free acid.