COPRECIPITATION OF THERMAL LYSINE-RICH PROTEINOIDS WITH POLYRIBONUCLEOTIDES

Major variables in interactions between basic thermal proteinoids and homopolyribonucleotides were magnesium concentration in solution (0-40 mM) and mol% lysine in the proteinoid (16-55%). The formation of microparticles was monitored both by the turbidity and by the mass of precipitate formed. Under some conditions, only, was the turbidity reading a reliable indication of the amount of precipitate. Increasing concentration of Mg2+ tended to displace proteinoid from the complex with polynucleotide. Of 4 polynucleotides, only polyguanylic acid showed an enhanced precipitation of proteinoid in the presence of Mg2+, and then only with those having high lysine contents. At high lysine contents, the amount of proteinoid in the precipitate was inversely proportional to the lysine content of the proteinoids, probably due to decreased sidechain interactions. The precipitation with polynucleotides is partly a function of the amino acid composition of the proteinoid; therefore the interaction of thermal proteinoids with polynucleotides appears to be a tool that can be used to study specificities of interactions between proteins and nucleic acids. © 1979.