Trypanosoma cruzi: aminoacid and phosphorus linkages in the lipopeptidophosphoglycan

The lipopeptidophosphoglycan (LPPG) of Trypanosoma cruzi was examined by 31P NMR spectroscopy. The main signal occurred at +0.67 ppm and corresponds to phosphodiester bonds. The presence of a signal at -25.06 indicates the existence of P-C linkages. At pH 10.5 signals which correspond to phosphate monoesters have been also obtained. Experiments on the stability of the phosphate bonds indicate that most of the monoester phosphates in LPPG are generated by alkaline hydrolysis of phosphodiester bonds. Aminoacid analysis of a LPPG hydrolysate revealed two pre-aspartic acid peaks with elution times coincident with those for authentic samples of 2-amino-3-phosphono-propionic acid and 2-aminoethyl-phosphonic acid in a 2.5:1 ratio. The main aminoacids in LPPG are Gly, Ser, Glu, Ala, Asp and Thr. Approximately half of the total aminoacids are released under saponification conditions indicating that part of the aminoacids in LPPG are bound via ester bonds.