title: Regulation of the concentration of free arachidonic acid in homogenates of human platelets.
abstract: With the intention to study the regulation of the availability of free arachidonic acid through the enzymes of the Lands cycle, we established a model system in homogenates of human platelets. Phospholipase A2, arachidonoyl-CoA synthetase and lysophosphatidyl acyltransferase proved to be simultaneously active and a steady turnover of arachidonic acid was the consequence. EGTA suppressed the deacylating activity that acted on endogenous membrane phospholipids and prevented eicosanoid formation from previously esterified exogenous arachidonoyl-CoA. The reacylating enzymes took part in the control of eicosanoid biosynthesis by re-esterification of liberated arachidonic acid. Blockade of the reacylation by apyrase made arachidonic acid completely available for further metabolization into 12-HETE and thereby induced an increase in the eicosanoid release.
authors.affiliation: Institute for Clinical Chemistry, Klinikum Mannheim, University of Heidelberg, Germany.
authors.forename: I
authors.initials: I
authors.lastname: Preuss
authors.forename: H
authors.initials: H
authors.lastname: Patscheke
mesh_terms: D008243:1-Acylglycerophosphocholine O-Acyltransferase / Q000097:blood; D000214:Acyl Coenzyme A / Q000097:blood; D001081:Apyrase / Q000097:blood; D016718:Arachidonic Acid / Q000097:blood*; D001792:Blood Platelets / Q000201:enzymology / Q000378:metabolism*; D003640:Dealkylation; D015777:Eicosanoids / Q000096:biosynthesis; D006801:Humans; D066298:In Vitro Techniques; D010741:Phospholipases A / Q000097:blood; D054467:Phospholipases A2; D010743:Phospholipids / Q000097:blood; D014280:Triglycerides / Q000097:blood
chemical_list: D000214:Acyl Coenzyme A; D015777:Eicosanoids; D010743:Phospholipids; D014280:Triglycerides; C026563:arachidonyl-coenzyme A; D016718:Arachidonic Acid; D008243:1-Acylglycerophosphocholine O-Acyltransferase; D010741:Phospholipases A; D054467:Phospholipases A2; D001081:Apyrase