Regulation of the concentration of free arachidonic acid in homogenates of human platelets.
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.
Preuss
I
I
Institute for Clinical Chemistry, Klinikum Mannheim, University of Heidelberg, Germany.
Patscheke
H
H
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
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