Ribonucleic Acids From Yeast Which Contain a Fifth Nucleotide

All recent methods for the isolation of the ribonucleic acids from yeast yield only 20 to 70 per cent of the ribonucleic acids that can be assumed to be present on the basis of quantitative analyses. There have been no studies regarding the nature of the ribonucleic acids that are lost during isolation, but it has tacitly been assumed that those which are lost have the same properties as those which are isolated. In the procedure of Crestfield, Smith, and Allen (I), 60 to 70 per cent of the ribonucleic acids from bakers’ yeast is isolated by a final precipitation from a 1 M solution of sodium chloride at 0”. 10 to 20 per cent of the total ribonucleic acids of the yeast is soluble in a 1 M solution of sodium chloride, together with certain proteins and deoxyribonucleic acids. The present communication deals with the isolation, purification, and characterization of the ribonucleic acids which are soluble in sodium chloride, and also describes the isolation and certain properties of a fifth nucleotide component which became evident in studying the action of ribonuclease on these ribonucleic acids. Preparation of Fractions