Characterization of Glycogen and Amino Acid Pool of Entamoeba histolytica by 13C‐NMR Spectroscopy

Abstract
Trophozoite extracts of axenic Entamoeba histolytica were investigated by natural-abundance 13C-NMR spectroscopy. The extracts were found to contain a high level of glycogen (30 mM glucose equivalents), which had a compact structure as suggested by α (1 → 6) branch points every 5–6 glucose residues. As other major metabolites, we identified putrescine (9.5 mM) and the following free amino acids: tyrosine and phenylalanine (1 mM), glycine, lysine and methionine (2 mM), isoleucine (5 mM), proline and valine (6–7 mM), leucine (11 mM) and glutamate (22 mM). Glutamate and proline may serve, together with putrescine, as intracellular osmolytes.