Some properties of lysyl ribonucleic acid synthetase from Escherichia coli.

Abstract

When the lysyl‐RNA synthetase from Escherichia coli was incubated with ATP and L‐lysine in the presence of Mg++, a complex of lysyl‐RNA synthetase, AMP and lysine was formed. The complex was isolated by filtration on Sephadex G‐25. Maximum complex formation was obtained at a molar ratio of substrate to enzyme between 3 and 4. The complex was very stable at low temperatures in the absence of Mg++, while incubation at 45° for 10 minutes gave 75% breakdown of the complex. The amino acid of the complex could be transferred to transferRNA in a reversible reaction that did not require Mg++. The transfer reaction was enhanced by the monovalent cations NH4+, Na+, and K+.The lysyl‐RNA synthetase from E. coli recognized about 70% of the lysine specific chains of yeast transferRNA, while the yeast enzyme recognized about 80% of the lysine specific chains of E. coli transferRNA. The esterification of E. coli transferRNA by the yeast enzyme proceeded at only 2% of the rate obtained with homologous transferRNA, while the E. coli enzyme esterified yeast transferRNA at about 60% of the rate obtained with E. coli transferRNA.