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KMID : 0624620110440010040
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BMB Reports
2011 Volume.44 No. 1 p.40 ~ p.45
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Inactive extracellular superoxide dismutase disrupts secretion and function of active extracellular superoxide dismutase
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Jeon Byeong-Wook
Kim Byung-Hak
Lee Yun-Sang
Kim Sung-Sub
Yoon Jong-Bok
Kim Tae-Yoon
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Abstract
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Extracellular superoxide dismutase (EC-SOD) is an antioxidant enzyme that protects cells and tissues from extracellular damage by eliminating superoxide anion radicals produced during metabolism. Two different forms of EC-SOD exist, and their different enzyme activities are a result of different disulfide bond patterns. Although only two folding variants have been discovered so far, five folding variants are theoretically possible. Therefore, we constructed five different mutant EC-SOD expression vectors by substituting cysteine residues with serine residues and evaluated their expression levels and enzyme activities. The mutant EC-SODs were expressed at lower levels than that of wild-type EC-SOD, and all of the mutants exhibited inhibited extracellular secretion, except for C195S ECSOD. Finally, we demonstrated that co-expression of wild-type EC-SOD and any one of the mutant EC-SODs resulted in reduced secretion of wild-type EC-SOD. We speculate that mutant EC-SOD causes malfunctions in systems such as antioxidant systems and sensitizes tissues to ROS-mediated diseases.
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KEYWORD
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Disulfide bond, EC-SOD, Proteasomal degradation, Secretion, Tetramer
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