Faculty Collaboration Database

Protective action of phospholipid hydroperoxide glutathione peroxidase against membrane-damaging lipid peroxidation. In situ reduction of phospholipid and cholesterol hydroperoxides. J Biol Chem 1990 Jan 05;265(1):454-61

Date

01/05/1990

Pubmed ID

2294113

Scopus ID

2-s2.0-0025060737 (requires institutional sign-in at Scopus site)   494 Citations

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.

Author List

Thomas JP, Maiorino M, Ursini F, Girotti AW

Authors

Albert W. Girotti PhD Adjunct Professor in the Biochemistry department at Medical College of Wisconsin
James P. Thomas MD, PhD Professor in the Medicine department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Animals
Cholesterol
Erythrocyte Membrane
Free Radicals
Glutathione Peroxidase
Humans
Kinetics
Lipid Peroxidation
Lipid Peroxides
Oxidation-Reduction
Phospholipids
Photochemistry
Swine
Tetramethylphenylenediamine
Thiobarbiturates