PURIFICATION OF THE CHLOROPLASTIC VALYL-TRANSFER RNA-SYNTHETASE FROM EUGLENA-GRACILIS

Euglena gracilis chloroplast valyl-tRNA synthetase was purified 990 fold to a specific activity of about 1100 units/mg protein, by a series of steps including ammonium sulfate precipitation and chromatography on hydroxyapatite, DEAE-cellulose, Blue Dextran - Sepharose and Sephadex G200. The enzyme gives a single band upon polyacrylamide gel electrophoresis, appears to be a monomer with a molecular weight of 126,000 daltons and has Km values of 1.5 × 10-5 M for L-valine, 5 × 10-5 M for ATP, and 6 × 10-8 for tRNAVal. © 1979.