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

摘要

>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.