Metabolism of N-acylethanolamine Phospholipids by a Mammalian Phosphodiesterase of the Phospholipase D Type

Rat heart contains a membrane-bound phosphodiesterase of the phospholipase D type which catalyzes the hydrolysis of 1,2-diacyl-sn-glycero-3-phospho(N-acyl)ethanolamine to N-acylethanolamine and phosphatidic acid. The enzyme also hydrolyzes the corresponding alkenylacylglycerophospho(N-acyl)ethanolamine and N-acylethanolamine lysophospholipids but not phosphatidylcholine or phosphatidylethanolamine. The activity is highest in the microsomal fraction, does not require Ca2+ or Mg2+, and is stimulated by Triton X-100. Bile salts, other ionic detergents, and Zn2+ are inhibitory. Hydrolysis occurs over a wide pH range, with the activity at acid pH being stimulated by freezing and thawing. Other rat tissues also release N-acylethanolamine from N-acylethanolamine phospholipids.