Polynucleotide-dependent incorporation of amino acids in a cell-free system from thermophilic bacteria.

The preparation of a cell-free amino acid incorporation system from Bacillus stearothermophilus active at 65” and the conditions for optimal activity with synthetic polynucleotide messengers are described. The activity of this system is comparable to that of the conventional Escherichia coli system. Its thermal stability, high activity, and low nuclease content are convenient features for studies of protein synthesis and coding. Thus, a 1.4: 1 copolymer of adenylic and uridylic acids, which, because of a high degree of ordered structure, is almost inactive in the E. co2i system at 3’7’, promoted significant incorporation of isaleucine, leucine, and lysine in the B. stearothermophilus system at 65“.