Chromatographic characterization of amino acid transfer and microsomal ribonucleic acids isolated from yeast.

Fresh bakers’ yeast was obtained from the Red Star Company, Cleveland, Ohio. The procedure for the isolation of the RNA fractions and their designation were those of Crestfield et al. (3) and Davis and Allen (4). Briefly, 150-g batches of finely divided yeast were heated 1 minute at 83-87” and 2 minutes at 80” in a solution of 2% recrystallized Duponol C (sodium lauryl sulfate, U.S.P., du Pont), 4.5% ethanol, and 0.025 M potassium phosphate buffer, pH 6.85. The solution was cooled and centrifuged at 0”. The RNA in the supernatant solution was precipitated and washed with ethanol and then redissolved in water. Sodium chloride was then added to the RNA solution to a final concentration of 1 M. The RNA in the gel which formed was separated by centrifugation and designated RNA A. The RNA in the supernatant fraction was reprecipitated with ethanol and redissolved in a smaller volume of water. Sodium chloride was added to a final concentration of 1 M. The RNA in the precipitate which formed was designated RNA B. The RNA precipitable by ethanol from the final supernatant fraction was called RNA C. After the initial column chromatographic experiment, which established the similarity of the major portions of RNA B and RNA C, they were isolated as a single fraction, RNA B + C, from the supernatant fraction after the separation of RNA A. The isolated RNA A and RNA B -fC fractions were treated by the phenol procedure (5). The fractions A, B, and C, and those isolated by ultracentrifugation were characterized by chromatography on Ecteola (Kutlir Laboratories, Monmouth Junction, New Jersey) ion exchange adsorbent (Column A) as described elsewhere (1,2). RNA I can be eluted from Ecteola adsorbent with a neutral salt solution. A large scale preparation of RNA I was as follows: a column of Ecteola adsorbent 6.5 cm in diameter and 8.5 cm high was prepared