12] Preparation of alkyl ether and vinyl ether substrates for phospholipases

Abstract

Publisher Summary This chapter describes the procedures of isolating alkyl ether and 1ʹ-alkenyl ether glycerophospholipids that can serve as substrates for phospholipases A 2 , C, or D, or for phosphatidate phosphohydrolase. The chapter primarily focuses on the preparation of representative phospholipid classes and species and reports variations in standard procedures that facilitate the synthesis of radioactively labeled phospholipids for use in phospholipase assays. A convenient source of isolating choline or ethanolamine plasmalogens are beef heart choline or ethanolamine phospholipids, which contain approximately 50% plasmalogens. The diacyl subclass can be selectively removed either by mild alkaline hydrolysis or by treatment with a regiospecific lipase, such as Rhizopus lipase, which attacks only the acyl ester bond in the sn -1 position of diacylglycerophospholipids and converts them to lysophospholipids. Catalytic hydrogenation of the vinyl ether double bond converts plasmalogens or lysoplasmalogens to alkyacylglycerophosphocholines and alkylglycerophosphocholines, respectively. Acylation of the latter, with acetic acid or fatty acid anhydrides, provides a straightforward method for synthesizing platelet-activating factor or alkylacylglycerophosphocholines of defined acyl chain composition.