Glutathione peroxidase activity of human erythrocyte membranes
Földes-Papp, Z.; Maretzki, D.
Acta Biologica et Medica Germanica 41(11): 1003-1008
1982
ISSN/ISBN: 0001-5318 PMID: 7170868 Document Number: 195933
A membrane bound glutathione peroxidase activity (GSH-Px activity) of human erythrocytes was found with t-butyl hydroperoxide as substrate. The portion of membrane bound GSH-Px activity ranged from 2.8%-6.8% of the whole cellular enzyme activity. At pH 7.0 and 1 mM GSH, the GSH-Px activity of hypotonically prepared membranes annouced to 3.8 .mu.mol GSH/ml erythrocytes .cntdot. h in a GSH generating system. At pH 8.0 and 2 mM GSH, the GSH-Px activity was .apprx. 7-fold higher in in hypotonic membranes and was slightly increased in isotonically prepared membranes. A GSH consumption by the GSH-Px activity of 1.4 .mu.mol GSH/ml erythrocytes .cntdot. h was calculated from GSH decay in isotonic membranes. About 50% of the cellular glutathione peroxidase activity assayed according to Beutler et al. are caused by the methemoglobin reductase. Under extreme oxidative challenges on the erythrocyte membrane the maintenance of the high ratio of GSH/GSSG is due to the cytosolic glutathione reductase.