Use of chromatofocusing in the purification of tryptophanyl-tRNA synthetase from Bacillus stearothermophilus

We have used chromatofocusing as the final stage in purifying tryptophanyl-tRNA synthetase from Bacillus stearothermophilus. Partially purified protein containing approximately 12% (w/w) synthetase was applied to the resin as a precipitate suspended in application buffer since both the desired enzyme and other proteins in this fraction were insoluble at low ionic strength. Nevertheless, homogeneous enzyme of higher specific activity than that...