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Copolymers of vinyl bases with acrylic acid and styrene or 1-vinyluracil with maleic acid were found to stimulate in vitro polyphenylalanine synthesis using a system extracted from Escherichia coli MRE600. Poly(styrene-maleic acid) was found to inhibit a ribosomal bound ribonuclease. Poly(1-vinyluracil, maleic acid), poly(1-vinyluracil, acrylic acid), and poly(9-vinyladenine, acrylic acid) were not inhibitors of the ribosome bound ribonuclease. The potent (up to fivefold) stimulation by these three polymers is due to the action of the polymers to interfere with ribosomal bound inhibitory protein. A protein, removed by washing ribosomes with 1 M ammonium chloride, characterized by M.J. Miller, A. Niveleau, and A.J. Wahba ((1974) J. Biol. Chem. 249, 3803) has been described as a potent inhibitor of in vitro poly(U)-coded protein synthesis using extracts of Escherichia coli MRE 600.

Radical-induced copolymerization of 1-vinyluracil and maleic anhydride gave, after hydrolysis, a polymer containing a 1:1 monomer ratio of 1-vinyluracil-maleic acid. Gamma-Ray-induced copolymerization of 1-vinyluracil with acrylic acid gave a polymer with a ratio of 1:1.7. Similar treatment of 9-vinlyadenine and acrylic acid resulted in a polymer with a 1:3.2 ratio. These three compounds are potent stimulants of poly (uridylic acid) coded polyphenylalanine synthesis in an in vitro cell free system purified from Escherichia coli MRE 600. The double-stranded polymer, poly(inosinic acid)-poly(cytidylic acid), also stimulates polyphenylalanine synthesis in this assay.