Non-reactivity of the selenoenzyme glutathione peroxidase with enzymatically hydroperoxidized phospholipids.
Selenium-containing glutathione peroxidase (EC 1.11.1.9) was purified 6000-fold from bovine red blood cells to apparent homogeneity. Lipoxygenase (EC 1.13.11.12) was enriched 20-fold from soybean acetone powder. Linoleic acid was peroxidized with lipoxygenase and then used as a substrate in the glutathione peroxidase reaction. Analogous experiments were conducted with synthetic 1,2-dilinoleoyl-L-alpha-glycerophosphocholine and with natural bovine heart cardiolipin. The peroxidized phospholipids were reactive with glutathione peroxidase only after enzymatic attack by phospholipase A2 (EC 3.1.1.4). This result implies that the membrane-protective function of glutathione peroxidase includes preceeding phospholipase action and excludes a direct interaction of this enzyme with membrane-bound lipid hydroperoxides.
D000818:Animals; D002417:Cattle; D055598:Chemical Phenomena; D002621:Chemistry; D005979:Glutathione Peroxidase / Q000378:metabolism*; D008054:Lipid Peroxides / Q000378:metabolism*; D008084:Lipoxygenase / Q000378:metabolism; D008563:Membrane Lipids / Q000378:metabolism; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D010743:Phospholipids / Q000378:metabolism*; D013379:Substrate Specificity
D008054:Lipid Peroxides; D008563:Membrane Lipids; D010743:Phospholipids; D005979:Glutathione Peroxidase; D008084:Lipoxygenase