Schistosoma mansoni: fractionation and characterization of the glycocalyx and glycogen-like material from cercariae.

The glycocalyx (GCX) that covers schistosomal cercariae is a complex molecule that has immunomodulating properties. Here, we purified milligram amounts of GCX using Anguilla lectin which binds to the GCX covering the cercarial body and tail. Typically, 10 million cercariae were extracted with phenol, dialyzed, and chromatographed on a Sepharose 2B-CL column. An average of 39 mg of total carbohydrate eluted near the void volume from which 31 mg of glycogen-like material was further separated by lectin affinity chromatography. Its identity was established by compositional analysis, sensitivity to amylase digestion, and its nuclear magnetic resonance spectrum. The lectin-bound GCX was eluted with 0.1 M fucose with a final yield of 5.3 mg carbohydrate. Fucose composed 40% of the total GCX carbohydrate with lesser but approximately equal amounts of galactose, glucosamine, and galactosamine present. NMR data indicated that the amino sugars were N-acetylated. Glucose was also present but in varying amounts in different preparations of GCX. Oligosaccharides were released from GCX by hydrazinolysis and separated by electrophoresis after reductive amination to 8-aminonaphthalene-1,3,6-trisulfonic acid (ANTS). Bands comigrating with standards containing 11, 12, 16, and 17 sugar residues were detected. Thus, the GCX is a complex structure composed of oligosaccharides, probably linked to a peptide.