31P-NMR analysis of Entamoeba histolytica. Occurrence of high amounts of two inositol phosphates.

Perchloric-acid extracts of axenic Entamoeba histolytica were investigated by 31P-NMR spectroscopy. All major 31P resonances observed were assigned to specific compounds. The cells contained inorganic phosphate (1039 nmol/g wet cells), pyrophosphate (16 nmol/g wet cells), nucleoside diphosphates (91 nmol/g wet cells), nucleoside triphosphates (275 nmol/g wet cells), NAD(P) (60 nmol/g wet cells), phosphocholine (184 nmol/g wet cells), phosphoethanolamine (214 nmol/g wet cells), cytidine 5'-diphosphocholine (41 nmol/g wet cells) and cytidine 5'-diphosphoethanolamine (55 nmol/g wet cells). The latter four compounds may act as intermediates in the salvage pathway for the synthesis of phosphatidylethanolamine and phosphatidylcholine. E. histolytica trophozoites also contained two inositol phosphates in large quantities, InsP3 (0.26 mumol/g wet cells) and InsP7 (0.11 mumol/g wet cells). These components were identified by 31P-NMR, using homonuclear J-resolved and two-dimensional 1H-31P correlative, analyses as myo-inositol trisphosphate, Ins(2,4,6)P3, and pentakisphospho-myo-inositol diphosphate, Ins(1,2,3,4,6)P5(5)P2.