Linked Life Data

14746474

Source:http://linkedlifedata.com/resource/pubmed/id/14746474

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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
2004-1-28
pubmed:abstractText
Trans unsaturated fatty acids in humans may be originated by two different contributions. The exogenous track is due to dietary supplementation of trans fats and the endogenous path deals with free-radical-catalyzed cis-trans isomerization of fatty acids. Arachidonic acid residue (5c,8c,11c,14c-20:4), which has only two out of the four double bonds deriving from the diet, was used to differentiate the two paths and to assess the importance of a radical reaction. A detailed study on the formation of trans phospholipids catalyzed by the HOCH2CH2S* radical was carried out on L-alpha-phosphatidylcholine from egg lecithin and 1-stearoyl-2-arachidonoyl-L-alpha-phosphatidylcholine (SAPC) in homogeneous solution or in large unilamellar vesicles (LUVET). Thiyl radicals were generated from the corresponding thiol by either gamma-irradiation or UV photolysis, and the reaction course was followed by GC, Ag/TLC, and 13C NMR analyses. The isomerization was found to be independent of cis double bond location (random process) in i-PrOH solution. In the case of vesicles, the supramolecular organization of lipids produced a dramatic change of the isomerization outcome: (i) in egg lecithin, the reactivity of arachidonate moieties is higher than that of oleate and linoleate residues, (ii) in the linoleate residues of egg lecithin, the 9t,12c-18:2 isomer prevailed on the 9c,12t-18:2 isomer (3:1 ratio), and (iii) a regioselective isomerization of SAPC arachidonate residues occurred in the 5 and 8 positions. This effect of "positional preference" indicates that thiyl radicals entering the hydrophobic region of the membrane bilayer start to isomerize polyunsaturated fatty acid residues having the double bonds nearest to the membrane surfaces. We propose that arachidonic acid and its trans isomers can function as biomarkers in membranes for distinguishing the two trans fatty acid-forming pathways.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0002-7863
pubmed:author
pubmed:issnType
Print
pubmed:day
4
pubmed:volume
126
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1063-72
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2004
pubmed:articleTitle
Regioselective cis-trans isomerization of arachidonic double bonds by thiyl radicals: the influence of phospholipid supramolecular organization.
pubmed:affiliation
I.S.O.F., Consiglio Nazionale delle Ricerche, Via P. Gobetti 101, 40129 Bologna, Italy. cferreri@isof.cnr.it
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't