Incomplete aminoacylation of tRNALeu catalyzed in vitro by leucyl-tRNA synthetase from Escherichia coli B.
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 vo-1 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. vo-1. 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.
D000604:Amino Acyl-tRNA Synthetases / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D007930:Leucine; D007935:Leucine-tRNA Ligase / Q000378:metabolism*; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism*; D046249:Transfer RNA Aminoacylation
D012346:RNA, Transfer, Amino Acyl; D000604:Amino Acyl-tRNA Synthetases; D007935:Leucine-tRNA Ligase; D007930:Leucine