A soluble fraction requirement in the transfer reaction of protein synthesis by rice embryo ribosomes.

The requirements for the transfer of (14)C-phenylalanine from yeast soluble ribonucleic acid to protein in vitro by rice (Oryza sativa L. var. Bluebonnet) ribosomes have been investigated. An absolute requirement for polyuridylic acid, 2-mercaptoethanol, guanosine triphosphate, magnesium, and potassium or ammonium ions and ribosomes has been demonstrated. Ribosomes washed in 0.5% sodium deoxycholate also required the presence of rice supernatant. The optimum concentration of magnesium ion for the reaction was approximately 7 mm, while 60 mm of either ammonium or potassium ion gave maximum transfer of phenylalanine in this heterologous system. The optimum concentration of guanosine triphosphate required varied with the presence or absence of the phosphoenolpyruvate-pyruvate kinase generating system. Without the system, the optimum concentration was 1.5 mm, but in its presence the optimum was approximately 0.1 mm.