A Simplified Procedure for the Preparation of Tyrosine- and Valine-Acceptor Fractions of Yeast “Soluble Ribonucleic Acid”

The first steps in the biosynthesis of proteins are believed to involve the enzymatic activation of the amino acids with adenosine triphosphate (ATP) followed by the transfer of the amino acids to amino acid-specific ribonucleic acids (RNA) (for a recent review see ( 1)).Studies of the separation of the different amino acid-specific RNAs by countercurrent distribution have been described recently (2-4).Of great interest is the finding that certain of the different amino acid-specific RNAs have widely different partition coefficients in a two-phase solvent system composed of concentrated pH 6 phosphate buffer, formamide, and isopropanol.In particular the tyrosine-and valine-specific RNAs have partition coefficients that differ by a factor of approximately 10.The difference is so great that almost complete separation of these amino acid-specific RNAs can be achieved in a small countercurrent distribution carried out in only a few tubes.The present paper describes in detail such a simple procedure for the separation of the tyrosine-and valine-specific RNAs.The starting material is yeast "soluble-RNA" prepared by a simplified procedure, and a simplified preparation of activating enzymes suitable for use in the assay of the tyrosine-and valine-acceptor fractions is also described.