Purification and properties of a glutathione peroxidase from Southern bluefin tuna ('Thunnus maccoyii') liver

Thompson, Janene L; Thomas, Philip; Schuller, Kathryn A

doi:10.1016/j.cbpb.2006.01.011

Author(s)

Thompson, Janene L

Thomas, Philip

Schuller, Kathryn A

Publication Date

2006

Abstract

A glutathione peroxidase (GPX) protein was purified approximately 1000-fold from Southern bluefin tuna (Thunnus maccoyii) liver to a final specific activity of 256 μmol NADPH oxidised min−¹ mg−¹ protein. Gel filtration chromatography and denaturing protein gel electrophoresis of the purified preparation indicated that the protein has a native molecular mass of 85 kDa and is most likely a homotetramer with subunits of approximately 24 kDa. The Km values of the purified enzyme for hydrogen peroxide, cumene hydroperoxide, t-butyl hydroperoxide and glutathione were 12, 90, 90 and 5900 μM, respectively. The Km values for cumene hydroperoxide and t-butyl hydroperoxide were approximately 8-fold greater than the Km value for hydrogen peroxide. Thus, the SBT liver GPX has a considerably greater affinity for hydrogen peroxide than for the other two substrates. The pH optimum of the purified enzyme was pH 8.0. Immunoblotting experiments with polyclonal antibodies, raised against a recombinant human GPX, provided further evidence that the purified SBT enzyme is a genuine GPX.

Citation

Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology, 144(1), p. 86-93

ISSN

1878-1659

1532-0456

Link

https://hdl.handle.net/1959.11/5969

Language

en

Publisher

Elsevier Inc

Title

Purification and properties of a glutathione peroxidase from Southern bluefin tuna ('Thunnus maccoyii') liver

Type of document

Journal Article

Entity Type

Publication

Author(s)	Thompson, Janene L Thomas, Philip Schuller, Kathryn A
Publication Date	2006
Abstract	A glutathione peroxidase (GPX) protein was purified approximately 1000-fold from Southern bluefin tuna (Thunnus maccoyii) liver to a final specific activity of 256 μmol NADPH oxidised min−¹ mg−¹ protein. Gel filtration chromatography and denaturing protein gel electrophoresis of the purified preparation indicated that the protein has a native molecular mass of 85 kDa and is most likely a homotetramer with subunits of approximately 24 kDa. The Km values of the purified enzyme for hydrogen peroxide, cumene hydroperoxide, t-butyl hydroperoxide and glutathione were 12, 90, 90 and 5900 μM, respectively. The Km values for cumene hydroperoxide and t-butyl hydroperoxide were approximately 8-fold greater than the Km value for hydrogen peroxide. Thus, the SBT liver GPX has a considerably greater affinity for hydrogen peroxide than for the other two substrates. The pH optimum of the purified enzyme was pH 8.0. Immunoblotting experiments with polyclonal antibodies, raised against a recombinant human GPX, provided further evidence that the purified SBT enzyme is a genuine GPX.
Citation	Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology, 144(1), p. 86-93
ISSN	1878-1659 1532-0456
Link	https://hdl.handle.net/1959.11/5969
Language	en
Publisher	Elsevier Inc
Title	Purification and properties of a glutathione peroxidase from Southern bluefin tuna ('Thunnus maccoyii') liver
Type of document	Journal Article
Entity Type	Publication

Purification and properties of a glutathione peroxidase from Southern bluefin tuna ('Thunnus maccoyii') liver

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