Studies on the Chemical Structure of Yeast Amino Acid Acceptor Ribonucleic Acids.

Elucidation of the nucleotide sequence of amino acid acceptor ribonucleic acid may reveal the structural basis of its amino acid specificity. The task appears feasible in the near future because of the low molecular weight attributed to S-RNA’ and because of the purity of the S-RNA preparations achieved so far. Ingram and Pierce (l), McCully and Cantoni (2), and Bell, Tomlinson, and Tener (3) have determined the base ratios and oligonucleotide distribution in specific enzymatic digests of crude S-RNA preparations, and Holley et al. (4) reported the base ratios and chromatographic profiles of enzymatic digests of purified alanine-, valine-, and tyrosine-S-RNA. Lagerkvist and Berg investigated the nucleotide sequences adjacent to the pCpCpA end of crude S-RNA (5)) and of leucineand isoleucineS-RNA (6). The studies on purified S-RNA revealed significant differences between the nucleotide sequences of individual amino acid acceptor RNA preparations (Holley et al. (4) ; Berg, Lagerkvist, and Dieckmann (6)). This report describes the quantitative determination of the major monoand oligonucleotides in pancreatic ribonuclease digests (7) from yeast alanineand tyrosine-S-RNA purified by countercurrent distribution with two solvent systems (8, 9). Our results indicate large variations between the nucleotide sequences of these two S-RNA preparations, in agreement with data obtained by other methods for the same RNAs by Holley (4).