Lysolecithin Metabolism by Human Platelets

Human platelets incubated with ³²P lysolecithin convert this compound to platelet lecithin and the water-soluble product glycerylphosphorylcholine. Lecithin synthesis from lysolecithin by intact platelets has a pH optimum of 9, whereas platelet homogenates show a pH optimum of 7.5 for the same reaction. Conversion of lysolecithin to platelet lecithin takes place by direct acylation of lysolecithin with free fatty acid. Addition of thrombin or ADP to the incubation medium has no effect on lysolecithin acylation or breakdown and does not affect the degradation of ¹⁴C choline-labeled platelet lecithin. Polystyrene particles stimulate lecithin synthesis and lysolecithin breakdown to glycerylphosphorylcholine by intact platelets but have no effect when added to platelet homogenates. By converting lysolecithin to lecithin, platelets add 2% to their lecithin content in 1 hr.