The preparation and characterization of ribonucleic acids from yeast.

Considerable variation in composition occurs among samples of ribonucleic acids from yeast. These variations are due in part to the procedures that are employed for isolation and subsequent purification. A recent study by Loring, Fairley, and Seagran (1) notes that variations may be due to (a) the occurrence of different ribonucleic acids in the particulate components of cells, (b) partial enzymatic degradation, and (c) partial chemical degradation. All methods recently published for isolation have sought to avoid partial chemical degradation by complete abandonment of earlier draskc procedures which incorporated the use of extremes in pH and prolonged treatment by heat. However, in discarding drastic methods and accepting milder methods which involve lengthy extractions at physiological pH, the way has been opened for enzymatic degradation to occur in a considerable degree. That enzymatic degradation may occur during procedures to isolate ribonucleic acids from tissues was first demonstrated by Bather and Allen (2). Volkin and Carter (3), by the use of guanidine hydrochloride, and Kay and Dounce (4), by the use of sodium dodecyl sulfate, have developed procedures to minimize enzymatic degradation. However, neither of the procedures effects the complete inhibition of crystalline ribonuclease from beef pancreas.’ The rapidity of destruction of ribonucleic acids in yeast is shown by a recent report of Bourdet and Mandel (5) wherein autolysis for 10 minutes at 50” destroys 93 per cent of the nucleic acids originally present. The procedure to be described was designed specifically to eliminate enzymatic degradation as a factor during isolation. The ribonucleic acids that have been isolated by the use of this procedure differ significantly in certain properties from samples described heretofore.