N-Acylation of ethanolamine phospholipids in canine myocardium.
N-Acylethanolamine phospholipids, which are found in infarcted but not in normal canine myocardium, were produced by preparations of normal myocardial tissue incubated in the presence of millimolar concentrations of Ca2+. Biosynthetic activity from endogenous substrates was associated with both microsomal and mitochondrial fractions and exhibited an alkaline pH optimum. The time course of N-acylethanolamine phospholipid synthesis and degradation was followed after pulse labeling of myocardial ethanolamine phospholipids with [1,2-14C]ethanolamine. Enzymic N-acylation of both phosphatidylethanolamine and lysophosphatidylethanolamine was demonstrated by incubating these substrates with homogenates of myocardial tissue. Neither free fatty acids nor acyl-CoA derivatives served as acyl donor but some of the constituent fatty acids of exogenous phosphatidylethanolamine were recovered among the amide-linked fatty acids of the N-acylethanolamine phospholipids. N-Acylation may thus occur by the transfer of O-acyl groups catalyzed by a Ca2+ -dependent transacylase. Since N-acylethanolamine phospholipids are precursors of the biologically active N-acylethanolamines, their biosynthesis may constitute an important injury-induced metabolic event aimed at the protection of ischemic myocardial tissue.
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002855:Chromatography, Thin Layer; D004285:Dogs; D004983:Ethanolamines / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D009206:Myocardium / Q000378:metabolism*; D010169:Palmitic Acids / Q000378:metabolism; D010171:Palmitoyl Coenzyme A / Q000378:metabolism; D010743:Phospholipids / Q000096:biosynthesis*; D013347:Subcellular Fractions / Q000378:metabolism
D004983:Ethanolamines; C022203:N-acylethanolamines; D010169:Palmitic Acids; D010743:Phospholipids; D010171:Palmitoyl Coenzyme A; D002118:Calcium