Studies of the Interaction between Aminoacyl‐tRNA Synthetase and Transfer Ribonucleic Acid by Equilibrium Partition

Abstract
The partition behavior of isoleucyl-tRNA synthetase [EC 6.1.1.5] and leucyl-tRNA synthetase [EC 6.1.1.4, from Escherichia coli], and tRNA in aqueous 2-phase systems composed of the polymers poly(ethyleneglycol) and dextran was investigated. A 2-phase system could be derived which can be used to study the interactions between synthetases and their cognate tRNAs by equilibrium partition. These measurements show that in each case 1 molecule of cognate tRNA is bound/molecule of enzyme. The binding constants were in the range 1-5 .mu.M-1. Equilibrium partition is apparently a useful method to study the interactions between macromolecules.