|
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 |
Family |
2.6.1.5.a |
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 |
2019/05/13 09:56 |
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