Purification and characterization of human plasma glutathione peroxidase: A selenoglycoprotein distinct from the known cellular enzyme☆

摘要: Glutathione peroxidase (GSHPx), (glutathione:H2O2 oxidoreductase, EC 1.11.1.9) was purified to homogeneity from human plasma. This resulted in a 6800-fold purification of the enzyme with 2.8% yield. The process involved ammonium sulfate fractionation, DEAE-cellulose batch and column chromatographies, hydroxyapatite, Sephadex G-200 DEAE-Sephadex A-25 chromatographies. major peak on chromatography found be homogeneous poly-acrylamide gel electrophoresis presence or absence sodium dodecyl (SDS). Relative mobility nondenaturing polyacrylamide at pH 8.2 0.5 for as detected by both protein staining activity compared 0.38 erythrocyte GSHPx. molecular weight plasma determined filtration approximately 100,000. SDS-gel gave subunit 23,000. suggests that exists tetramer its native state, similar seen enzyme, but slightly different electrophoresis. Plasma GSHPx, like contain four atoms selenium per mole protein. Utilizing iodinated concanavalin A, it not GSPx, is glycoprotein. Purified catalyzes reduction tertiary butyl hydroperoxide hydrogen peroxide. apparent Km GSHPx GSH 5.3 mm 0.57 mm. Copper, mercury, zinc strongly inhibit Rabbit antibodies directed against do precipitate enzyme. Radioimmunoassay utilizing anti-erythrocyte showed less than 0.13% antigenically detectable