certain aminoacyl-trna synthetases , including the e. coli , yeast , and calf liver asparagine and tyrosine activating enzymes , the e. coli and yeast cysteinyl-trna synthetases , and the aspartyl-trna synthetase from yeast , utilized both isomeric trnas as substrates , although generally not at the same rate .
C0002529
aminoacyl-trna synthetases
C0004022
aspartyl-trna synthetase