Multinuclear NMR spectroscopy of the cellular slime mold Polysphondylium pallidum. Monitoring of the encystment and excystment processes

Heteronuclear NMR studies of metabolites produced by Cryptococcus neoformans in culture media: identification of possible virulence factors

The yeast, Cryptococcus neoformans var. neoformans is a major contributor to the morbidity and mortality experienced by the immunosuppressed population. With a view to providing better treatment, identification of cryptococcal virulence factors is an important goal, with most effort to date directed toward the significance of structural variations in the polysaccharide capsule. The present work describes the characterization of supernatants obtained from cryptococcal cultures. This was achieved by thorough identification of the spin systems of individual metabolites through both homonuclear and heteronuclear NMR experiments that circumvented the difficulties imposed by limited dispersion and a range of concentrations in different cultures covering more than 3 orders of magnitude. More than 30 metabolites, including amino acids, alditols, nucleosides, acetate, and ethanol, were identified by their (1)H and (13)C chemical shifts and observed long-range correlations. The possible contribution of some detected substances to the pathogenicity of Cryptococcus neoformans is discussed. Magn Reson Med 42:442-453, 1999.

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.