The presence of inorganic polyphosphate in yeast RNA preparations has been proved by many investigators. The polyphosphate content of high molecular RNA was investigated and the nature of a linkage between such species of macromolecules discussed by Ebel et cd. ( 1). In the course of our experiments, an RNA of elevated labile phosphate content and insoluble in 1 M NaCl has been isolated (2) and the experiments concerning the effect of salt reprecipitation on the polyphosphate content of the RNA have been undertaken. METHODS Industrial baker's yeast (purchased from Z. P. R. Niechcice, Poland) was suspended in a synthetic medium (3) but the phosphate concentration was increased up to 2 gm KH,PO, per liter with no KC1 added. Cells (2.5 gm dry mass per liter) were incubated for 15 hr at 30°C, then centrifuged and washed with cold water. The high molecular RNA was isolated according to Crestfield et al. ( 4) and examined after dialysis against water. (Filtration through Celite and D-7 Steriflo asbestos pad was not used in our procedure.)
Two RNA preparations were examined. Aliquots of 0.5 ml of the RNA solution were treated at 0°C with successive amounts of NaCl, KCI, and (NH,) 80, or 0.5 M CaCl, and 0.5 M MgCI, solutions to obtain the final salt concentration as indicated in the tables.
Samples were kept at 0" and the precipitated gel was centrifuged. Precipitates were washed with corresponding salt solution at the concentration previously used for precipitation, and supernatants were combined. Estimations of total phosphorus (5) and orthophosphate hydrolyzed after heating with 1 N H&SO., for 10 min (PlO) (6) were carried out. Inorganic orthophosphate was determined according to Delsal and Manhouri (7).