The preparation of ribonucleoprotein from yeast.

The present work was undertaken to study the distribution of yeast nucleoprotein in cell fractions after centrifugal separation, and to define conditions of extraction and purification in order to obtain the nucleoprotein in a relatively undegraded state. Bakers’ yeast (Xaccharomyces cerevisiae) is the classical source of ribonucleic acid (RNA), but relatively little work has been reported on the nucleoproteins of this organism. Khouvine and de Robichon-Szulmajster (1) have isolated nucleoproteins from yeast by extraction with 0.2 per cent sodium bicarbonate. The cells had been dried with acetone and ether at 10” and ground in a cold ball mill. Three nucleoprotein fractions were obtained by precipitation at 4.96, 4.32, and 2.25 pH. These authors have reported on the composition of the protein (1) and nucleic acid (2) components and have described the effects of some variations of yeast strain and treatment (2, 3). The presence in yeast of submicroscopic particles rich in pentose nucleic acid has been reported by several workers (4-7). This paper reports the composition of several centrifugal fractions of ground yeast and of a nucleoprotein material isolated by pH adjustment.