Sialylation by recombinant trans-sialidase of the synthesized oligosaccharides, O-linked in Trypanosoma cruzi glycoproteins.

AGUSTI R; MENDOZA VM,; GIORGI M. E; GALLO- RODRIGUEZ C; LEDERKREMER RM

Pinamar, Argentina

Congreso; SAIB XLI Annual Meeting of the Argentine Society for Biochemistry and Molecular Biology; 2005

SAIB

The mucin-like glycoproteins of T. cruzi have novel O-linkedoligosaccharides which are acceptors of sialic acid in the transsialidase(TcTS) reaction. This process is involved in infection andpathogenesis. The O-chains may be derived from the two cores,Galp(β164)GlcNAc or Galf(β164)GlcNAc by further branchingwith various units of Galf and/or Galp. The presence ofgalactofuranose is related to the lineage and was found in the G,DM28C and Tulahuen strains of T. cruzi.We have chemically synthesized the oligosaccharides containing 3-5 sugar units. The acceptor properties were studied in order tocorrelate their structure with the ability to act as substrates.Recombinant TcTS (A. C. C. Frasch (UNSAM)), and sialyllactoseas donor were used. The reactions were analyzed by HPAEC-PAD.The Km values were calculated for the free sugars and the benzylglycosides. The highest affinity was shown by the trisaccharide.The pentasaccharide, the major O-linked sugar in the mucins,presents two terminal β-D-Galp for possible sialylation. Apreparative TS reaction was performed with the benzyl glycosideof the pentasaccharide. One of the two external Galp units wasselectively sialylated, as shown by NMR spectroscopy.