Abstract
A procedure is described for the purification of the aspartate:tRNA ligase [EC 6.1.1.12] from E. coli to a stage where it was homogeneous by polyacrylamide gel electrophoresis. From the same batch of E. coli the lysine, phenylalanine and serine ligases [EC 6.1.1.6, EC 6.1.1.20 and EC 6.1.1.11, respectively] were obtained in an apparently homogeneous form while the alanine, glutamine, leucine and valine enzymes [EC 6.1.1.7, EC 6.1.1.18, EC 6.1.1.4 and EC 6.1.19, respectively] had a purity varying from 20-80%. Aspartate:tRNA ligase, which was not obtained in a highly purified form before, was characterized in terms of its molecular parameters.