A Lens Glutathione S-transferase, Class Mu, with Thiol-specific Antioxidant Activity

A protein that protected against the thiol-mediated metal-catalysed oxidative inactivation of enzymes but did not protect against the ascorbate-dependent oxidation system was extensively purified from bovine lens. The protein was a homodimer (pI 7) of 26kDa subunits. Sixty per cent of the protein se...

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Bibliographic Details
Published in:Experimental eye research 2000-09, Vol.71 (3), p.255-265
Main Authors: Jimenez-Asensio, Jose, Garland, Donita
Format: Article
Language:English
Subjects:
Animals
Antioxidants - metabolism
Biological and medical sciences
bovine
Cattle
cDNA
Cloning, Molecular
DNA, Complementary - metabolism
Eye and associated structures. Visual pathways and centers. Vision
Fundamental and applied biological sciences. Psychology
glutathione S-transferase
Glutathione Transferase - chemistry
Glutathione Transferase - classification
Glutathione Transferase - physiology
lens
Lens, Crystalline - enzymology
metal-catalysed oxidation
oxidation
Oxidation-Reduction
protein
Sequence Analysis, DNA
Sequence Analysis, Protein
Sulfhydryl Compounds - physiology
thiol-specific antioxidant
Vertebrates: nervous system and sense organs
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Summary:A protein that protected against the thiol-mediated metal-catalysed oxidative inactivation of enzymes but did not protect against the ascorbate-dependent oxidation system was extensively purified from bovine lens. The protein was a homodimer (pI 7) of 26kDa subunits. Sixty per cent of the protein sequence was obtained by Edman sequencing and by sequence comparison was determined to be a class μ glutathione S-transferase (GST). The sequence of the enzyme is homologous to, but not identical to, that of any other class μ GST in the databanks. The complete protein sequence was derived from sequencing the cDNA and is the first complete sequence of a class μ GST from a bovine tissue. The enzyme was cloned and expressed in E. coli. The recombinant GST also protected against the thiol-mediated oxidative inactivation of enzymes but with lower activity than the native enzyme did and the recombinant GST had a comparable higherKm for GSH. The native and recombinant enzymes possessed similar low level peroxidase activity utilizing alkyl and cumene peroxides as substrates, but exhibited little activity against hydrogen peroxide.
ISSN:0014-4835
1096-0007
DOI:10.1006/exer.2000.0876