Antigenic determinants sialyl

Structurally, the O-polysaccharide chains of H. pylori clinical isolates have a poly-A-acetyl-lactosamine (-LacNAc) chain decorated with multiple lateral a-L-fucose residues forming internal Lex determinants with terminal Lex or Ley units (Fig. 10.4) or, in some strains with additional, D-glucose or D-galactose residues (Moran 2001 a,b, 2008 Monteiro, 2001). Moreover, Lea, Leb, sialyl-Lex, and H-1 antigens have been structurally described in other strains, as well as the related blood groups A and B (Fig. 10.4), but occur in association with Lex and LacNAc chains (Monteiro et al., 2000a,b Heneghan et al., 2000). 

The first enzyme we evaluated for its ability to transfer unnatural sugars was the human Lewis a(l- 4)fucosyltransferase (FucT). This particular enzyme was chosen because of its potential utility in the synthesis of the tumor associate sialyl-Lewis-a antigen Q2) <1 analogs thereof. In addition, the enzyme could be quite readily obtained in a soluble form with high specific activity from human milk. The a(l- 4)FucT catalyzes reaction I below which results in the production of the Lewis-a trisaccharide determinant... 

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