Magic-angle spinning ³¹P NMR spectroscopy of condensed phosphates in parasitic protozoa: Visualizing the invisible

We report the results of a solid-state ³¹P nuclear magnetic resonance (NMR) spectroscopic investigation of the acidocalcisome organelles from Trypanosoma brucei (bloodstream form), Trypanosoma cruzi and Leishmania major (insect forms). The spectra are characterized by a broad envelope of spinning sidebands having isotropic chemical shifts at ∼0,-7 and-21 ppm. These resonances are assigned to orthophosphate, terminal (α) phosphates of polyphosphates and bridging (β) phosphates of polyphosphates, respectively. The average polyphosphate chain length is ∼3.3 phosphates. Similar results were obtained with whole L. major promastigotes. ³¹P NMR spectra of living L. major promastigotes recorded under conventional solution NMR conditions had spectral intensities reduced with respect to solution-state NMR spectra of acid extracts, consistent with the invisibility of the solid-state phosphates. These results show that all three parasites contain large stores of condensed phosphates which can be visualized by using magic-angle spinning NMR techniques.