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

AGUSTI, R; MENDOZA, VM; GALLO-RODRIGUEZ, C; GIORGI, ME; MUCHNIK DE LEDERKREMER, R

Pinamar – Buenos Aires

Congreso; SAIB (Sociedad Argentina de Investigación en Bioquímica y Biología Molecular) 41th Annual Meeting; 2005

  The mucin-like glycoproteins of T. cruzi have novel O-linked oligosaccharides which are acceptors of sialic acid in the trans-sialidase (TcTS) reaction. This process is involved in infection and pathogenesis.1 The O-chains may be derived from the two cores, Galp(b1→4)GlcNAc or Galf(b1→4)GlcNAc by further branching with various units of Galf and/or Galp. The presence of galactofuranose is related to the lineage and was found in the G, DM28C and Tulahuen strains of T. cruzi (Figure 1).  We have chemically synthesized the oligosaccharides containing 3-5 sugar units.2,3 The acceptor properties were now studied in order to correlate their structure with the ability to act as substrates. Recombinant TcTS (A.C.  Frasch (UNSAM)), and sialyllactose as donor were used. The reactions were analyzed by HPAEC-PAD.4 The Km values were calculated for the sugar alditols and the benzyl glycosides. All the compounds showed to be good acceptors of sialic acid, being the tetrasaccharide derivatives the less efficient.  The pentasaccharide 4, the major O-linked sugar in the mucins, presents two terminal b-D-Galp for possible sialylation. We have previously shown that 2,3-di-O-(b-D-Galp)-Galp was selectively sialylated.5 A preparative TS reaction was performed now with the benzyl glycoside 8 of the pentasaccharide