Studies on microbial protein synthesis with Azotobacter vinelandii as the test organism I. Incorporation of radioactive phosphate and sulfate into the resting cells in the presence of antibiotics and antimetabolites

The effects of the three antibiotics, chloramphenicol, streptomycin and penicillin and two antimetabolites, p-fluorophenylalanine and 8-azaguanine, on the synthesis of nucleic acid and protein in Azotobacter vinelandii were investigated by studying the kinetics of incorporation of radioactive phosphate and sulfate into the resting cells. The results are in general agreement with those obtained with other microorganisms and indicate that nucleic acid plays a direct part in protein synthesis and that the reverse phenomenon does not occur

Studies on microbial protein synthesis with Azotobacter vinelandii as the test organism II. Incorporation of radioactive amino acids into protein of cell-free particulate preparations

It has been found that a cell-free particulate preparation from A. vinelandii sedimentable at low gravitational field (2,000-30,000 × g) actively incorporates the amino acids, glycine, glutamate and leucine, into protein. The requirements of the incorporating system have been studied in detail. Treatment of the particles with NaCl reduces their incorporating activity to a considerable extent. Rat-liver pH 5 fraction or pH 5 fraction prepared from A. vinelandii extracts reactivates the particles. The bacterial pH 5 fraction can also substitute for the rat-liver pH 5 fraction in its capacity of incorporating amino acids into microsomes of rat liver