Selective transfers of acetylenic acids to form lecithins.

Although acetylenic acids are not normally found in mammalian tissues, octadecynoyl-CoA esters can serve as substrates for rat liver microsomal acyl-CoA: phospholipid acyltransferases. The relatively high rate of transfer to the 2-hydroxyl of I-acylglycerol-3-phosphorylcholine by the 5-, 9-, and I2-positional cis, tram and yne isomers of acids supports the concept that n-bonds at these positions facilitate esterification irrespective of configuration. The preferred positional isomers for transfer to the I-hydroxyl, however, are different for the cis and yne derivatives, indicating a sensitivity of the enzyme(s) to configuration. In the latter transfer, an alternating selectivity occurred with the acetylenic isomers between 8 to 13 that was opposite to the pattern for the cis-octadecenoyl transfers.