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Transfer ribonucleic acid nucleotidyltransferase from Escherichia coli. II. Purification, physical properties, and substrate specificity.

Abstract Transfer RNA nucleotidyltransferase (EC 2.7.7.25) from Escherichia coli has been purified to near homogeneity. The apparent molecular weight of the enzyme is about 50,000 as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration. No evidence for subunits was obtained. The enzyme is rapidly and irreversibly inactivated in the absence of magnesium. The enzyme incorporates only 1 AMP and 2 CMP residues into tRNA from which the terminal -pC-C-A had been removed. All E. coli amino acid acceptor tRNA species as well as heterologous tRNA can serve as substrates.