Histidyl Transfer Ribonucleic Acid Synthetase From Bakers' Yeast

Histidyl-t-RNA synthetase has been purified 590-fold from toluene lysates of bakers' yeast (Saccharomyces cereviseae). Lysis with toluene inactivates most other synthetases. Further purification was achieved by precipitation with ammonium sulfate followed by chromatography on DEAE-cellulose and on calcium phosphate gel. Extensive loss of enzymic activity was noted during chromatography on DEAE-cellulose unless a hydrogen bonding substance, such as propylene glycol, was added to the eluting system. The purified enzyme was free of other aminoacyl-t-RNA synthetase activities except that for tryptophanyl-t-RNA and a trace of that for aspartyl-t-RNA. It was free of peptidase activity.