Sialic acid in a complex oligosaccharide chain of the Tc-85 surface glycoprotein from the trypomastigote stage of Trypanosoma cruzi

The carbohydrate moiety of the Tc-85 surface glycoprotein from the infective trypomastigote form of Trypanosoma cruzi was analysed. Tc-85 could be metabolically labeled by incubation of the cells with D-14C]mannose or D-14C]glucose. Degradation techniques were performed directly on the polyacrylamide gel band containing labeled Tc-85. A mannobiose was cleaved by beta-elimination and further treatment of the remaining material under conditions which liberate N-asparaginyl linkages, released a complex oligosaccharide. The presence of sialic acid was demonstrated by: mild acid hydrolysis, neuraminidase treatment and periodate oxidation under mild conditions followed by NaB3H4 reduction, hydrolysis, and detection of NANA7 by paper electrophoresis. In addition, the chromatographic behavior of the asialooligosaccharide was significantly different from that of the original sample. Galactose, mannose and glucosamine are the other monosaccharide components of the sialooligosaccharide.