Purification of five serine transfer ribonucleic acid species from Escherichia coli and their acylation by homologous and heterologous seryl transfer ribonucleic acid synthetases.

Escherichia coli tRNA has been fractionated on benzoylated DEAE-cellulose and DEAE-Sephadex to yield five purified tRNASer species. They differ in chromatographic behavior and in their coding properties. These tRNASer species are all charged by pure E. coli seryl-tRNA synthetase. Four of the tRNAs exhibit the same K, and V,,,,, in this reaction. For one of the tRNAs (the least pure) these parameters could not be measured because of substrate inhibition. Partially purified seryl-tRNA synthetase from yeast or from Neurospora crassa can esterify serine to all of the purified isoacceptor RNAs. However, the extent of charging is only a small fraction of the level obtained with the homologous seryl-tRNA synthetase.