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Metabolism of epoxidized phosphatidylcholine by phospholipase A 2 and epoxide hydrolase
Author(s) -
Sevanian Alex,
Stein Robert A.,
Mead James F.
Publication year - 1981
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/bf02535029
Subject(s) - epoxide hydrolase , phospholipid , microsomal epoxide hydrolase , biochemistry , epoxide , phosphatidylcholine , phospholipase a2 , chemistry , phospholipase , microsome , metabolism , hydrolysis , enzyme , membrane , catalysis
The isolation and measurement of phospholipid epoxides as major peroxidation products in biomembrane preparations prompted an investigation of enzymatic mechanisms which may be responsible for their elimination. Analysis of microsomal epoxide hydrolase and phospholipase A 2 activity against a phospholipid epoxide commonly encountered in tissues indicated it to be a poor substrate for epoxide hydrolase, but rapidly hydrolyzed by phospholipase A 2 . Microsomal and purified phospholipase A 2 preparations hydrolyzed the phospholipid epoxide at rates 2‐fold greater than were observed with a monoenoic phospholipid from which the epoxide would be derived. The product fatty acid epoxide, cis ‐9,10‐epoxystearic acid, was rapidly hydrated by microsomal and cytosolic epoxide hydrolase. On the basis of earlier reports demonstrating increased phospholipase activity against oxidized phospholipids, and on the results of the present study, a model for the metabolism of oxidized membrane phospholipids is proposed.