Stabilization and purification of tyrosine aminotransferase from rat liver.
Purification of unmodified tyrosine aminotransferase from rat liver requires that the activity of cathepsin T be minimized, and that losses of enzyme due to dilution or oxidation by prevented. The enzyme was stabilized by pyridoxal 5'-phosphate, dithiothreitol, and potassium phosphate, but was destabilized by L-tyrosine or L-glutamate. A rapid, efficient method for purification of this enzyme included the following steps: twenty-fold induction with a high-casein diet plus dexamethasone phosphate administered in the drinking water; a heat step (65 degrees C) followed by precipitation from 0.20 M sucrose at pH 5.0; and small-scale chromatography on DEAE-cellulose, hydroxyapatite and CM-Sephadex C50 at pH 6.0. These steps yielded more than 10 mg of native enzyme from 35 rats, with a recovery of 68% of the initial activity.
Hargrove
J L
JL
Department of Foods and Nutrition, University of Georgia, Athens 30602.
D000818:Animals; D002848:Chromatography, DEAE-Cellulose; D002852:Chromatography, Ion Exchange; D004790:Enzyme Induction; D004795:Enzyme Stability; D005260:Female; D008099:Liver / Q000201:enzymology*; D008297:Male; D051381:Rats; D014444:Tyrosine Transaminase / Q000302:isolation & purification* / Q000378:metabolism
D014444:Tyrosine Transaminase