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Activation of phospholipase A{sub 2} in 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine liposomes containing lipid ozonation products

Journal Article · · Chemical Research in Toxicology
; ;  [1]
  1. Louisiana State Univ., Baton Rouge, LA (United States)
The activation of phospholipase A{sub 2} (PLA{sub 2}) by lipid ozonation products is reported. The principal products from the ozonation of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) are 1-palmitoyl-2-[8-3(5-octyl-1,2,4-trioxolan-3-yl)octanoyl]--sn-glycero-3-phosphocholine (PC-Criegee ozonide) and 1-palmitoyl-2-(9-oxononanoyl)-sn-glycero-3-phosphocholine (PC-aldehyde). Here we test the hypothesis that these two compounds are mediators of ozone toxicity. Using POPC vesicles, we find that PLA{sub 2} recognizes and hydrolyzes PC-Criegee ozonide at the same rate as that of arachidonic acid. Although the PC-aldehyde is not a substrate for PLA{sub 2}, the enzymatic rate of hydrolysis by PLA{sub 2} of unaltered fatty acids incorporated into POPC is enhanced when PC-aldehyde is present in the bilayer. Thus, both PC-Criegee ozonide and PC-aldehyde alter the activity of PLA{sub 2}, perhaps via an effect on membrane packing order. The capacity of PLA{sub 2} to recognize the PC-Criegee, and therefore ozone-induced damage, suggests a detoxification property of the enzyme and also a role in maintaining the structural properties of bilayer membranes that have been altered by exposure to ozone. 29 refs., 3 figs., 1 tab.
Sponsoring Organization:
USDOE
OSTI ID:
50624
Journal Information:
Chemical Research in Toxicology, Journal Name: Chemical Research in Toxicology Journal Issue: 3 Vol. 7; ISSN CRTOEC; ISSN 0893-228X
Country of Publication:
United States
Language:
English