The incorporation of radioactive phosphate into the ribonucleic acid of cell-free preparations of Azotobacter vinelandii

Abstract

1. 1. A cell-free preparation from Azotobacter vinelandii is capable of incorporating [³²P]P_i into RNA in the presence of Mg²⁺ ions and 3-phosphoglyceric acid (or phosphoenol pyruvate). 2. 2. The 105 000 × g particulate fraction as well as the 105 000 × g supernatant fraction are essential for the incorporation. 3. 3. The incorporation is considerably stimulated by the addition of AMP, ADP, ATP or Poly-A at a concentration of 1.10^-3 M. Higher concentrations usually lead to inhibition. 4. 4. The possibility of the labelling of RNA by the freely reversible reaction catalysed by polynucleotide phosphorylase has been ruled out. 5. 5. The radioactive RNA isolated from the incubation mixture behaves as s-RNA and all of its four nucleotidic components are radioactive.