Protective action of phospholipid hydroperoxide glutathione peroxidase against membrane-damaging lipid peroxidation. In situ reduction of phospholipid and cholesterol hydroperoxides release_t4v74muq45bufe762zsp3abl2i

by J P Thomas, M Maiorino, F Ursini, A W Girotti

Published in Journal of Biological Chemistry.

1990   Volume 265, Issue 1, p454-61

Abstract

The general reactivity of membrane lipid hydroperoxides (LOOHs) with the selenoenzyme phospholipid hydroperoxide glutathione peroxidase (PHGPX) has been investigated. When human erythrocyte ghosts (lipid content: 60 wt % phospholipid; 25 wt % cholesterol) were treated with GSH/PHGPX subsequent to rose bengal-sensitized photoperoxidation, iodometrically measured LOOHs were totally reduced to alcohols. Similar treatment with the classic glutathione peroxidase (GPX) produced no effect unless the peroxidized membranes were preincubated with phospholipase A2 (PLA2). However, under these conditions, no more than approximately 60% of the LOOH was reduced; introduction of PHGPX brought the reaction to completion. Thin layer chromatographic analyses revealed that the GPX-resistant (but PHGPX-reactive) LOOH was cholesterol hydroperoxide (ChOOH) consisting mainly of the 5 alpha (singlet oxygen-derived) product. Membrane ChOOHs were reduced by GSH/PHGPX to species that comigrated with borohydride reduction products (diols). Sensitive quantitation of PHGPX-catalyzed ChOOH reduction was accomplished by using [14C]cholesterol-labeled ghosts. Kinetic analyses indicated that the rate of ChOOH decay was approximately 1/6 that of phospholipid hydroperoxide decay. Photooxidized ghosts underwent a large burst of free radical-mediated lipid peroxidation when incubation with ascorbate/iron or xanthine/xanthine oxidase/iron. These reactions were only partially inhibited by PLA2/GSH/GPX treatment, but totally inhibited by GSH/PHGPX treatment, consistent with complete elimination of LOOHs in the latter case. These findings provide important clues as to how ChOOHs are detoxified in cells and add new insights into PHGPX's protective role.
In text/plain format

Archived Files and Locations

application/pdf  3.1 MB
file_csx6rmhvyjcfvoc54h3yqvyww4
www.jbc.org (web)
web.archive.org (webarchive)
Read Archived PDF
Preserved and Accessible
Type  article-journal
Stage   published
Date   1990-01-05
Language   en ?
PubMed  2294113
Journal Metadata
Open Access Publication
In DOAJ
In Keepers Registry
ISSN-L:  0021-9258
Work Entity
access all versions, variants, and formats of this works (eg, pre-prints)
Catalog Record
Revision: 36e1b0cf-7e03-4aa8-bc4a-e059cfcf6031
API URL: JSON