title: neo-inositol polyphosphates in the amoeba Entamoeba histolytica.
abstract: We have reexamined the structure of inositol phosphates present in trophozoites of the parasitic amoeba Entamoeba histolytica and show here that, rather than being myo-inositol derivatives (Martin, J.-B., Bakker-Grunwald, T., and Klein, G. (1993) Eur. J. Biochem. 214, 711-718), these compounds belong to a new class of inositol phosphates in which the cyclitol isomer is neo-inositol. The structures of neo-inositol hexakisphosphate, 2-diphospho-neo-inositol pentakisphosphate, and 2, 5-bisdiphospho-neo-inositol tetrakisphosphate, which are present in E. histolytica at concentrations of 0.08-0.36 mM, were solved by two-dimensional (31)P-(1)H NMR spectroscopy. No evidence for the co-existence of their myo-inositol counterparts has been found. These neo-inositol compounds were not substrates of 6-diphospho-inositol pentakisphosphate 5-kinase, an enzyme purified from Dictyostelium discoideum that phosphorylates 6-diphospho-myo-inositol pentakisphosphate and more slowly also myo-inositol hexakisphosphate, specifically on position 5. Because preliminary data indicate that large amounts of the same neo-inositol phosphate and diphosphate esters are also present in another primitive amoeba, Phreatamoeba balamuthi, the occurrence of high concentrations of neo-inositol polyphosphates may be much more general than previously thought.
authors.affiliation: Département de Biologie Moléculaire et Structurale/Laboratoire de Résonance Magnétique en Biologie Métabolique, CEA-Grenoble, 38054 Grenoble, France.
authors.forename: J B
authors.initials: JB
authors.lastname: Martin
authors.forename: T
authors.initials: T
authors.lastname: Laussmann
authors.forename: T
authors.initials: T
authors.lastname: Bakker-Grunwald
authors.forename: G
authors.initials: G
authors.lastname: Vogel
authors.forename: G
authors.initials: G
authors.lastname: Klein
mesh_terms: D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004023:Dictyostelium / Q000201:enzymology; D004748:Entamoeba histolytica / Q000737:chemistry* / Q000254:growth & development; D007295:Inositol Phosphates / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D010766:Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D007295:Inositol Phosphates; D017853:Phosphotransferases (Alcohol Group Acceptor); C064990:inositol pentakisphosphate kinase