Rapid inactivation of the yeast phenylalanyl-tRNA synthetase in the course of aminoacylation of the heterologous E. coli tRNAPhe is observed. This inactivation occurs due to the formation of the tight complex of the enzyme with the pyrophosphate formed during the aminoacylation reaction. This complex is shown to be the normal intermediate of the reaction. Possible inactivation mechanism and correlation between structural differences of yeast and E. coli tRNAsPhe with the changes in the enzymatic mechanism of aminoacylation are discussed.
