BIOSYNTHESIS OF ALKYL GLYCERYL ETHERS BY MICROSOMAL ENZYMES OF DIGESTIVE GLANDS AND GONADS OF STARFISH, ASTERIAS FORBESI

1. 1. A microsomal enzyme system that can synthesize alkyl ether linkages in glycerolipids has been isolated from the digestive glands and gonads of the starfish, Asterias forbesi. The total lipids of the microsomes from the digestive glands contain approx. 4.5% alkyl glyceryl ethers and 5.5% alk-1-enyl glyceryl ethers. The chain lengths of alkyl moieties consist of 16:0 (31%), 18:0 (39%) and 20:1 (13%), whereas the chain lengths of the alk-1-enyl moieties consist mainly of 18:0 (79%). 2. 2. The biosynthetic system for alkyl ethers utilizes long-chain fatty alcohols and glyceraldehyde 3-phosphate as substrates and ATP, CoA, and Mg2+ as cofactors. The time-course for the reaction is linear for at least 90 min, and the products produced have chromatographic properties identical to those which we have found in microsomes from neoplastic cells. No alk-1-enyl glyceryl ethers are formed in this system. Gas-liquid chromatography of the 14C-labeled O-alkylglycerol isopropylidene derivatives (prepared after LiA1H4 reduction of total lipids) revealed that approx. 90% of the 14C was associated with the C16:0 glyceryl ether fraction after incubation of 14C labeled C16:0 fatty alcohol. © 1969.