title: Hepatic tyrosine aminotransferase from the rainbow lizard Agama agama: purification and some properties.
abstract: Tyrosine aminotransferase, induced by dexamethasone in the liver of the rainbow lizard, Agama agama, was extracted under optimal conditions which yield the native undegraded enzyme; purified by heat treatment at 65 degrees C, ammonium sulfate precipitation, chromatography on DEAE-Sephacel and Sephadex G-150-120 and then characterized. The enzyme was purified over 2000-fold to a specific activity of 2653 units/mg of protein. It had an optimum pH of 7.6 in potassium phosphate buffer, KmTyr: 1.0 mM; K alpha-KGm: 0.32 mM; Vmax: 1.33 nmol/min and a molecular weight of about 130,000. It was inhibited by L-glutamate (competitively, Ki, 2.5 mM), and by metal ions Ca2+, Mn2+, Zn2+, Hg2+ and Ag2+, but was unaffected by chelating agents and other divalent cations. Lizard hepatic cytosolic tyrosine aminotransferase was specific for L-tyrosine and alpha-ketoglutarate as substrates sensitive to sulfhydryl inactivation and to protection from thermal lability by alpha-ketoglutarate and pyridoxal phosphate.
mesh_terms: D000818:Animals; D002614:Chelating Agents / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D004790:Enzyme Induction / Q000187:drug effects; D005260:Female; D006863:Hydrogen-Ion Concentration; D008099:Liver / Q000201:enzymology*; D008116:Lizards / Q000378:metabolism*; D008297:Male; D008670:Metals / Q000494:pharmacology; D008970:Molecular Weight; D011489:Protein Denaturation; D011506:Proteins / Q000032:analysis; D013379:Substrate Specificity; D013438:Sulfhydryl Compounds / Q000494:pharmacology; D013696:Temperature; D014444:Tyrosine Transaminase / Q000032:analysis* / Q000302:isolation & purification
chemical_list: D002614:Chelating Agents; D008670:Metals; D011506:Proteins; D013438:Sulfhydryl Compounds; D014444:Tyrosine Transaminase