The N-linked carbohydrate chain of the 85-kilodalton glycoprotein from Trypanosoma cruzi trypomastigotes contains sialyl, fucosyl and galactosyl (alpha 1-3)galactose units.
The structure of the N-linked oligosaccharide of the 85-kDa surface glycoprotein (Tc-85) from the infective trypomastigote form of Trypanosoma cruzi was investigated. Tc-85 metabolically labeled with [14C]glucose was purified by affinity chromatography on wheat germ agglutinin-Sepharose. Binding to the lectin was lost on treatment of Tc-85 with neuraminidase. The N-linked asialo-oligosaccharide was released by endo-beta-N-acetylglucosaminidase F digestion of asialo-Tc-85 and was further analyzed using specific exoglycosidases. [14C]fucose was detected after alpha-L-fucosidase treatment or mild acid hydrolysis. The afucosyl oligosaccharide was 3H-labeled by the galactose oxidase-NaB3H4 method. [3H]Galactose was released by alpha-galactosidase, and only then was beta-galactosidase effective in removing another galactose. The gal(alpha 1-3)gal unit was demonstrated by periodate oxidation studies on the [3H]galactose-labeled asialo-glycoprotein. The presence of gal(alpha 1-3)gal in Tc-85 could be related to the recent finding of elevated antibody levels against this epitope in patients with Chagas' disease.
Couto
A S
AS
Departamento de Química Orgánica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Argentina.
Gonçalves
M F
MF
Colli
W
W
de Lederkremer
R M
RM
D000118:Acetylglucosaminidase; D000818:Animals; D004187:Disaccharides / Q000032:analysis; D005643:Fucose / Q000032:analysis; D006023:Glycoproteins / Q000032:analysis*; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase; D015394:Molecular Structure; D015800:Protozoan Proteins / Q000032:analysis*; D012794:Sialic Acids / Q000032:analysis; D014349:Trypanosoma cruzi / Q000502:physiology*
D004187:Disaccharides; D006023:Glycoproteins; D015800:Protozoan Proteins; D012794:Sialic Acids; C055075:galactosyl-(1-3)galactose; D005643:Fucose; D000118:Acetylglucosaminidase; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase