Further Evidence for a Single Leucyl Transfer Ribonucleic Acid Synthetase Capable of Charging Five Leucine Transfer Ribonucleic Acids in Escherichia coli

Five components of leucine transfer ribonucleic acid in Escherichia coli separated on a reversed phase column were charged with radioactive leucine.Each labeled leucyl-tRNA was subjected to an exchange reaction with unlabeled E. coti tRNA in which the labeled leucine could be transferred from one leucine tRNA to another.The 'exchange product, when analyzed on methylated albumin-Kieselguhr columns, suggested that a single leucyl-tRNA synthetase was responsible for the attachment of leucine to all five leucine tRNAs.The existence of a single synthetase specific for all five components of leucine tRNA was further supported by studying the reaction rate of mixed substrates containing two leucine tRNAs under a condition in which the rate was enzyme-dependent.