Phosphatidylethanolamine synthesis in the normal and lymphomatous mouse liver; a 13C NMR study

The lymphomatous liver contains high levels of phosphoethanolamine. This compound is a precursor of the phospholipid, phosphatidylethanolamine. The kinetics of phosphatidylethanolamine synthesis has been studied by 13C NMR spectroscopy of extracts of the lymphomatous mouse liver following the administration of (13C2)ethanolamine. The concentrations of (13C2)ethanolamine, (13C2)phosphoethanolamine, and (13C2)phosphatidylethanolamine were fitted to kinetic models and the maximal activities of the enzymes in the synthetic pathway were estimated. Phosphatidylethanolamine synthesis in the normal liver appears to be limited by the supply of ethanolamine. In the lymphomatous liver, both ethanolamine kinase and PE:CTP cytidylyltransferase had lower activities than in the normal liver, and there was evidence for a higher activity of ethanolamine base-exchange enzyme.