Phospholipids with a short acyl chain modulate phospholipase and acyltransferase activities

• Published in: Journal of lipid mediators and cell signalling 1995-07, Vol.12 (1), p.59-76
• Main Authors: Koumanov, Kamen S., Momchilov-Pankova, Albena B., Markovska, Tanna T., Quinn, Peter, Wolf, Claude
• Format: Article
• Language: English
• Subjects: 1-Acylglycerophosphocholine O-Acyltransferase - metabolism; Acyltranferase; Animals; Asymmetric phosphatidylcholines; Biomembranes; Calorimetry; Cell Membrane - chemistry; Cell Membrane - metabolism; Crystallography, X-Ray; Fluorescent Dyes; Hydrolysis; Liposomes - chemistry; Liver - ultrastructure; Male; Molecular Structure; Phosphatidylcholines - chemistry; Phosphatidylcholines - metabolism; Phosphatidylcholines - pharmacology; Phospholipase A 2; Phospholipases A - metabolism; Phospholipases A2; Rats; Rats, Wistar; Structure-Activity Relationship
• ISSN: 0929-7855
• DOI: 10.1016/0929-7855(95)00008-E

1-Acyl lysophosphatidylcholine prepared from egg yolk has been chemically reacylated to form decanoyl, dodecanoyl, myristoyl and palmitoyl derivatives of phosphatidylcholine. The liposomes formed by these semi-synthetic phospholipids have been characterized by calorimetry, X-ray diffraction and fluorescence probe methods. Asymmetric phosphatidylcholines tend to promote formation of excimers of a codispersed fluorescent phospholipid (1-palmitoyl- sn-2-(1-pyrenedecanoyl)- l-α-phosphatidic acid) (2 mol%). Excimer formation is correlated with the rate of hydrolysis of the fluorescent anionic phospholipid by Crotalus venom phospholipase A 2. Codispersion with the semi-synthetic phosphatidylcholine of cholesterol or unsaturated fluid lecithin modulated both excimer formation and the susceptibility of the fluorescent probe to hydrolysis by venom phospholipase A 2 at 22°C. Similar results were btained with hydrolysis of a radiolabelled substrate, 1-palmitoyl- sn-2-[1 14C linoleoylphosphatidylethanolamine, codispersed with the semi-synthetic phosphatidylcholine. Enrichment of rat hepatocyte plasma membranes with semi-synthetic asymmetric phosphatidylcholines was mediated by incubation of membranes with phospholipid dispersions in the presence of a phospholipid exchange protein. Enrichment of the membranes with semi-synthetic phosphatidylcholines of between 30 and 60% of the membrane phosphatidylcholine was achieved. The resulting alteration of the biomembrane is associated with a decreased activity of endogenous membrane phospholipase A 2 acting on extramembranous radiolabelled substrate vesicles. By contrast, the activity of acylCoAaysophospholipid acyltransferase is increased in membranes enriched with highly asymmetric phospholipids.