Metabolic relationship between arachidonate activation and its transfer to lysophospholipids by brain microsomes.
Evidence is presented to indicate a metabolic relationship between arachidonic acid activation and its transfer to lysophospholipids by brain microsomes. Thus, in the presence of 1-acylglycerophosphocholines or 1-acyl-glycerophosphoinositols, the activation of labeled arachidonate to its acyl-CoA was enhanced, and the acyl-CoA formed was, in turn, transferred to the lysophospholipids to form the respective diacyl-glycerophospholipids. The "coupling effect" seems to pertain mainly to the lysophospholipids which are good substrates of the acyltransferase. Other lyso-compounds were either not effective or inhibitory to the arachidonate activation process. The activation-transfer activity mediated by the fatty acid ligase and acyltransferase could be dissociated by Triton X-100, which apparently stimulated the acyl-CoA ligase activity but inhibited the acyltransferase. These results suggest that fatty acid ligase and acyltransferase are located in close proximity within the membrane domain. The existence of a close metabolic relationship between these two enzymic reactions is important for maintaining a dynamic equilibrium between the free fatty acids and the membrane phospholipids. The mechanism is also useful in regulating the cellular acyl-CoA and lysophospholipid metabolism, because both compounds have membrane perturbing properties when present in excessive quantity.
D000214:Acyl Coenzyme A / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism*; D001711:Biotransformation; D001921:Brain / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism; D006868:Hydrolysis; D066298:In Vitro Techniques; D008274:Magnesium / Q000378:metabolism; D008861:Microsomes / Q000378:metabolism*; D010743:Phospholipids / Q000096:biosynthesis / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
D000214:Acyl Coenzyme A; D001095:Arachidonic Acids; D005227:Fatty Acids; D010743:Phospholipids; D016718:Arachidonic Acid; D000255:Adenosine Triphosphate; D008274:Magnesium