The acylation of 1-acylglycero-3-phosphorylcholines by rat-liver microsomes

Abstract

1. 1. The transfer of acyl groups from acyl-coenzyme A derivatives to phosphatidylcholine by rat-liver microsomes was found to be significantly stimulated by the addition of synthetic 1-acylglycero-3-phosphorylcholines. Unsaturated acyl chains were transferred in preference to saturated ones, particularly when mixtures of CoA esters were present.

2. 2. Of the series of 1-acylglycero-3-phosphorylcholines studied, (carrying decanoate, myristate, stearate, oleate or linoleate) only 1-decanoylglycero-3-phosphorylcholine was found to be a poor acceptor in the acyl-transfer reaction. The fatty acyl constituent of the other lysolecithins studied exhibited limited influence on the rate of acyl transfer.

3. 3. Mixtures of various 1-acylglycero-3-phosphorylcholines were incubated with rat-liver microsomes in the presence of either labeled saturated or mono-unsaturated acyl-CoA derivatives. The radioactive lecithins synthesized were converted by phospholipase C (EC 3.1.4.3) into diglycerides which were separated in individual molecular species. The results demonstrated that under these conditions no preferential acylation of saturated, mono- or di-unsaturated lysolecithin occurred with either laurate, palmitate or oleate.

4. 4. These findings are discussed with respect to the distribution of fatty acyl moieties in rat-liver lecithin.