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Published on: August 7, 2014
The major selenium-containing protein in human peripheral granulocytes.
Q Liu1, E Lauridsen, J Clausen
1Department of Life Sciences and Chemistry, Roskilde University, Denmark.
Biological Trace Element Research
|May 18, 1999
Summary
Researchers purified and identified a novel selenium-containing peroxidase in human granulocytes. This enzyme eliminates hydrogen peroxide (H2O2), protecting cells during phagocytosis and potentially inhibiting glutathione peroxidase (GSH-Px).
Area of Science:
- Biochemistry
- Cell Biology
- Immunology
Background:
- A 15 kDa selenium-containing protein was previously identified in human granulocytes.
- This study focuses on the purification, identification, and characterization of this major selenium-containing protein.
Purpose of the Study:
- To purify and characterize the major selenium-containing protein from peripheral human granulocytes.
- To elucidate the enzymatic activity and biological function of this protein, particularly its role in oxidative stress defense.
Main Methods:
- Protein purification using heparin-Sepharose and Sephacryl S-200 chromatography.
- Analysis via SDS-PAGE, HPLC, high-performance gel filtration, and isoelectric focusing.
- Enzyme activity assays and inhibition studies with glutathione peroxidase (GSH-Px).
Main Results:
- Purified protein consists of two subunits around 15 kDa, containing selenocysteine/selenocystine.
- Apparent molecular weight of 32 kDa and pI of 7.9 were determined.
- The protein exhibits H2O2-dependent peroxidase activity, competing with GSH-Px and protected by sodium azide.
Conclusions:
- The identified protein is a novel H2O2-dependent selenium-containing peroxidase, distinct from GSH-Px.
- Its function is likely to eliminate H2O2 during granulocyte respiratory burst, protecting against phagocytic oxidative damage.
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