Cell-free Amino Acid-incorporating Systems from Bacillus licheniformis and Bacillus stearothermophilus 10

Cell-free amino acid-incorporating systems were prepared from log-phase cells of Bacillus licheniformis and B. stearothermophilus 10. No differences were observed between the two systems with respect to the types and relative amounts of the ribosomes, the time dependence of incorporation, and the optimal magnesium ion concentration (4 m m ). The B. licheniformis system showed greater dependence on added transfer ribonucleic acid (tRNA) and was less stimulated by polyuridylic acid (poly U) than the B. stearothermophilus 10 system. Neither system was saturated at a level of 450 μg of poly U per incubation mixture. The S-100 fraction and the isolated tRNA inhibited incorporation in the B. stearothermophilus 10 system at 55 C but not at 37 C. No such inhibition was observed in the B. licheniformis system at either temperature. The tRNA prepared from B. subtilis, B. licheniformis , or B. stearothermophilus 10 could be used interchangeably in the two cell-free systems.