Effect of spermine on the reaction catalyzed by threonyl-tRNA synthetase from rat liver

The effect of spermine on the rates of ATP-pyrophosphate exchange and of formation of threonyl-tRNA by threonyl tRNA synthetase has been studied. It is shown that spermine alone has no effect on the overall reaction as well as on the rate of ATP pyrophosphate isotope exchange. At low Mg2+ concentration spermine activates 8-fold the ATP-pyrophosphate isotope exchange and 23-fold the threonyl tRNA synthesis. The possible role of spermine in this activation is discussed.