The dependence of cell-free protein synthesis in E. coli upon naturally occurring or synthetic polyribonucleotides

template RNA.Other explanations, however, are fully plausible, and it is not possible at this state to rule out alternative interpretations.In the following paper, further experiments on amino acid incorporation using the system described here are presented.It will be shown that in addition to the usual requirements, the system is stimulated by template RNA.Summary.-Cell-free E. coli extracts have been obtained which actively in- corporate amino acids into protein.Methods were devised whereby these extracts could be dialyzed and stored for long periods of time at -150 without undue loss of activity.The characteristics of amino acid incorporation by such stored ex- tracts were strongly suggestive of de novo protein synthesis, for incorporation required both ribosomes and 105,000 X g supernatant fractions, ATP and an ATP- generating system, was stimulated by a mixture of other L-amino acids, and was markedly inhibited by puromycin, chloramphenicol, and RNAase.The initial rate of amino acid incorporation was not inhibited by DNAase; subsequent in- corporation was greatly inhibited.The possible relationship of the DNAase inhibition of amino acid incorporation into protein to the synthesis of "messenger" RNA was briefly discussed.