The extent of esterification of [14C]leucine into Escherichia coli B tRNALeu apparently depends on the concentration of leucyl-tRNA synthetase. The effect is more pronounced at pH 9.0 than at pH 7.4. When reciprocals of leucyl-tRNA concentration at plateau [aa-tRNA]-1 are plotted against reciprocals of initial velocities v-10 of aminoacylations a straight line is obtained with a slope equal to the rate constant of non-enzymatic deacylation of leucyl-tRNA. Factors which change the stability of leucyl-tRNA, e.g. pH and temperature, also change the shape of the function [aa-tRNA]-1 vs. v-10. The data are consistent with the idea that the rate constant of spontaneous deacylation of aminoacyl-tRNA is the factor which accounts for the dependence of the level of aminoacylation on initial velocity of aminoacylation.
All Science Journal Classification (ASJC) codes