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B6db references: 87271767

type Journal Article
authors Echetebu, C. O.; Ifem, F. M.; Echetebu, Z. O.
title Hepatic tyrosine aminotransferase from the rainbow lizard Agama agama: purification and some properties
journal Biochimie
Activity 2.6.1.5
ui 87271767
year (1987)
volume 69
number 3
pages 223-30.
 
keywords Animal
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.
last changed 2002/11/12 16:17

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