One-step purification of an alpha(1-3)-L-fucosyltransferase from human amniotic fluid by fetuin-agarose affinity chromatography

Expression of N-linked sialyl Le(x) determinants and O-glycans in the carbohydrate moiety of human amniotic fluid transferrin during pregnancy

Transferrin, a glycoprotein involved in iron transport in body fluids, was isolated from amniotic fluid of a hydramniospatient by sequential anion-exchange chromatography and gel filtration. The N-glycans of human amniotic fluid transferrin (hAFT) were enzymatically liberated by PNGase-F digestion, isolated by gel filtration and fractionated by (high-pH) anion-exchange chromatography. After alkaline borohydride treatment of native hAFT, the released O-glycans were isolated by gel filtration and fractionated by anion-exchange chroma-tography. Structure elucidation of 14 N- and 2 O-glycans was performed by 500 or 600 MHz1H-NMR spectroscopy. Besides conventional N-glycans established earlier for human serum transferrin (hST), new (alpha1-3)-fucosylated N-glycans were found, representing sialyl Le(x) elements. Furthermore, as compared to hST, a higher degree of (alpha1-6)-fucosylation and an increase in branching from di- to triantennary compounds has been detected. The presence of O-glycans is demonstrated for the first time in transferrin.

Synthesis of alpha-D-galactopyranosyl-linked oligosaccharides containing the alpha-Gal-->beta-Gal-->GlcNAc sequence employing methyl-2,3,4,6-tetra-O-(4-methoxybenzyl)-1-thio-beta-D-galactopyranosid e as an efficient glycosyl donor

Synthesis of two trisaccharides and a tetrasaccharide, namely, alpha-Gal-(1-->3)-beta-Gal-(1-->3)-GlcNAc-beta-OBn (6), alpha-Gal-(1-->3)-beta-Gal-(1-->4)-GlcNAc-beta-OBn (9) and alpha-Gal-(1-->3)-beta-Gal-(1-->4)-GlcNAc-beta-(1-->6)-GalNAc- alpha-OBn (19) was accomplished through development and utilization of a key alpha-galactosyl donor, methyl 2,3,4,6-tetra-O-(4- methoxybenzyl)-1-thio-beta-D-galactopyranoside (1).

Occurrence and specificities of α3-fucosyltransferases

The Le(x) (CD15) carbohydrate antigen and sialylated and oligomeric derivatives thereof have been implicated in cell adhesion processes. Expression of these antigens is developmentally regulated and (re)occurrence of several members of this group has been reported in malignant transformation of cells. Studies on the enzymology and genetics of alpha 3-fucosyltransferases, glycosyltransferases that play a key role in the biosynthesis of these antigens, would yield insight in the regulation of expression of these carbohydrate structures. In this paper the existing literature on these enzymes is reviewed and placed in the context of cell adhesion and malignancy.

Recognition by ELAM-1 of the sialyl-Lex determinant on myeloid and tumor cells

Endothelial leukocyte adhesion molecule-1 (ELAM-1) is an endothelial cell adhesion molecule that allows myeloid cells to attach to the walls of blood vessels adjacent to sites of inflammation. ELAM-1 recognizes the sialyl-Lewis X (sialyl-Lex) determinant, NeuAc alpha 2-3Gal beta 1-4(Fuc alpha 1-3)GlcNAc-, a granulocyte carbohydrate also found on the surface of some tumor cell lines. Binding of myeloid cells to soluble ELAM-1 is inhibited by a monoclonal antibody recognizing sialyl-Lex or by proteins bearing sialyl-Lex, some of which may participate in humoral regulation of myeloid cell adhesion. Stimulated granulocytes also release an inhibitor of ELAM-1 binding that can be selectively adsorbed by monoclonal antibody to sialyl-Lex.