[Affinity modification of phenylalanyl-tRNA-synthetase in the presence of ligands].

The kinetics of the affinity modification of phenylalanyl-tRNA synthetase from E. coli MRE-600 with chb-tRNA was used for investigation of copling between the binding sites of tRNA and other ligands. It was shown that ATP, phenylalanine and their mixture do not change the efficiency of complex formation but decrease specifically the rate of enzyme alkylation. L-Tyrosine and L-valine do not influence the enzyme alkylation. ATP is more effective protector than L-phenylalanine. In the presence of both ATP and phenylalanine the enzyme alkylation is excluded. The possibilities of this method for studying the coupling between binding sites are discussed.