Document Detail


Discovery of an arachidonoyl coenzyme A synthetase in human platelets.
MedLine Citation:
PMID:  7061494     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Platelets contain small amounts of a variety of free fatty acids but essentially no free arachidonate. When free fatty acids are incubated with platelets, there is preferential incorporation of arachidonic acid and 8,-11,14-eicosatrienoic acid compared to other fatty acids. We now explain these findings by the discovery that platelets contain two long chain acyl-CoA synthetases. One shows activity with a range of different fatty acids, similar to long chain acyl-CoA synthetases studied previously. A crude platelet membrane preparation contains this enzyme that catalyzes the formation of 0.75 nmol of oleoyl-CoA/min/10(9) platelets. The other enzyme is specific for the prostaglandin precursors arachidonic acid and 8,11,14-eicosatrienoic acid. Based on the ability of fatty acids to inhibit arachidonate and 8,11,14-eicosatrienoate activation, we conclude that other fatty acids including linoleic, 5,8,11-eicosatrienoic, and oleic acids are not substrates for the enzyme. Platelet membranes catalyze formation of 2.9 nmol of arachidonoyl-CoA/min/10(9) platelets and 2.5 nmol of 8,11,14-eicosatrienoyl-CoA/min/10(9) platelets. Arachidonoyl-CoA synthetase has optimal activity at pH 8 and requires ATP (Km = 0.5 mM), Mg2+ (Km = 2.5 mM), CoA (Km = 0.13 mM), and arachidonic acid (Km = 0.03 mM). We propose that the arachidonate-specific acyl-CoA synthetase may control the level of free arachidonic acid in platelets, limiting prostaglandin synthesis by the unstimulated cell and capturing free arachidonate from extracellular sources.
Authors:
D B Wilson; S M Prescott; P W Majerus
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  257     ISSN:  0021-9258     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  1982 Apr 
Date Detail:
Created Date:  1982-05-27     Completed Date:  1982-05-27     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  3510-5     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Animals
Blood Platelets / enzymology*
Cell Membrane / enzymology
Coenzyme A Ligases / blood*,  metabolism
Fatty Acids, Unsaturated / pharmacology
Humans
Kinetics
Microsomes, Liver / enzymology
Rats
Substrate Specificity
Grant Support
ID/Acronym/Agency:
HL 07088/HL/NHLBI NIH HHS; HL 16634/HL/NHLBI NIH HHS; HLBI 14147/HL/NHLBI NIH HHS
Chemical
Reg. No./Substance:
0/Fatty Acids, Unsaturated; EC 6.2.1.-/Coenzyme A Ligases; EC 6.2.1.15/arachidonate - CoA ligase

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