A selenium-containing catalytic antibody (Se-4A4), prepared by converting reactive serine residues of a monoclonal antibody (4A4) raised against a GSH derivative into selenocysteines, acts as a mimic of cytosolic glutathione peroxidase (cGPX). To clarify the mechanism of action of this catalytic antibody, detailed studies on kinetic behaviour and biological activity were carried out. A rate of acceleration (kcat/Km/kuncat) 107-fold that of the uncatalytic reaction is observed. Under similar conditions, the turnover number (kcat) of Se-4A4 is 42% of that of the natural rabbit liver cGPX. The Se-4A4 reaction involves a Ping Pong mechanism, which is the same as that of the natural cGPX. The selenocysteine residue is located in the binding site of the antibody and is shown to be crucial for this activity. Of the thiol compounds tested, only GSH is able to serve as substrate for Se-4A4. It was demonstrated, using the free-radical-damage system (hypoxanthine/xanthine oxidase) of cardiac mitochondria, that Se-4A4 can protect mitochondria from free-radical damage at least 104-fold more effectively than the natural cGPX.
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May 1998
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Research Article|
May 15 1998
Biochemical characterization of selenium-containing catalytic antibody as a cytosolic glutathione peroxidase mimic Available to Purchase
Lan DING;
Lan DING
1
*Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, People's Republic of China
1To whom correspondence should be addressed.
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Zi LIU;
Zi LIU
†The National Laboratory of Enzyme Engineering, Jilin University, Changchun 130023, People's Republic of China
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Zhenqi ZHU;
Zhenqi ZHU
†The National Laboratory of Enzyme Engineering, Jilin University, Changchun 130023, People's Republic of China
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Guimin LUO;
Guimin LUO
†The National Laboratory of Enzyme Engineering, Jilin University, Changchun 130023, People's Republic of China
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Daqing ZHAO;
Daqing ZHAO
*Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, People's Republic of China
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Jiazuan NI
Jiazuan NI
*Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, People's Republic of China
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Publisher: Portland Press Ltd
Received:
August 28 1997
Revision Received:
December 17 1997
Accepted:
January 12 1998
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London © 1998
1998
Biochem J (1998) 332 (1): 251–255.
Article history
Received:
August 28 1997
Revision Received:
December 17 1997
Accepted:
January 12 1998
Citation
Lan DING, Zi LIU, Zhenqi ZHU, Guimin LUO, Daqing ZHAO, Jiazuan NI; Biochemical characterization of selenium-containing catalytic antibody as a cytosolic glutathione peroxidase mimic. Biochem J 15 May 1998; 332 (1): 251–255. doi: https://doi.org/10.1042/bj3320251
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