All‐Transglycolytic Synthesis and Characterization of sialyl(α2–3)galactosyl(β1–4)xylosyl‐p‐nitrophenyl(β1–, an Oligosaccharide Derivative Related to Glycosaminoglycan Biosynthesis

Abstract

P-D-Xylopyranosides, such as p-nitrophenyl-P-D-xylopyranoside (Xyl-Np) or 4-methylumbelliferyl-P-D-xylopyranoside (Xyl-MeUmb), when added to the culture medium of human skin fibroblasts have previously been shown to produce some Np-or MeUmb-oligosaccharides related to the regulation of glycosaminoglycan biosynthesis. Among these oligosaccharide derivatives, we synthesized the trisaccharide derivative NeuAc(a2-3)Gal(P1-4)Xyl-Np@l-as a potential inhibitor of human skin fibroblast glycosaminoglycan biosynthesis. This synthesis was achieved by sequential use of transglycosylating activities of Escherichia coli P-galactosidase and Tvpanosornu cruzi trans-sialidase. The structure of the oligosaccharide obtained was determined by HPLC, ion-spray mass spectrometry, and NMR.Keywords: transgl ycosylation; trans-sialidase ; glycosaminoglycan ; NMR.In the last decade, the importance of carbohydrates as modulators of biological activity has become increasingly more evident. Antigenic determinants, receptors for proteins, viruses or bacteria involve carbohydrate moieties, and other important biological events, such as cell-cell recognition and interactions, are carbohydrate-mediated events (Gleeson, 1994;Dwek, 1996). Therefore, the availability of synthetic oligosaccharides potentially allows for control of most of these biological activities. Accordingly, new carbohydrate-based therapeutics, that are able to mimic biological phenomena, have been developed (Hodgson, 1991 ;Zopf and Roth, 1996). The overall synthetic approaches for the synthesis of oligosaccharides have been remarkably improved. Chemical synthesis is still the most used method, but it is certainly also the most time consuming approach. Enzymatic approaches are becoming more attractive because of their selectivity. Glycosyltransferases are probably the most powerful tools, but their extreme specificity and the high cost of the natural substrates (NDP-sugars) make them less applicable for largescale preparative applications (Ichikawa et al., 1992;Wong et al., 1995). From a practical point of view, the use of glycosidases for transglycosylation reactions is more interesting. They are versatile and their synthetic activities can be modulated by changing various experimental parameters (Nilsson, 1987(Nilsson, , 1988aCote and Tao, 1990;Bucke and Rastall, 1990;Usui, 1992;Vetere and Paoletti, 1996a).In the framework of our research devoted to the enzymatic synthesis of biologically important oligosaccharides using transglycosylation reactions, we started the synthesis of NeuAc(a2-3)Gal(b1-4)Xyl-Np@l-by exclusive use of transglycosylation activities of Escherichia coli P-galactosidase and Trypanosoma cruzi trans-sialidase. It is well known that derivatives of xylose such as 4-methylumbelliferyl-~-~-xylopyranoside (XylMeUmb) and p-nitrophenyl-a-D-xylopyranoside (Xyl-Np) stimulate the synthesis of glycosaminoglycans in cells from a variety of tissues (Okoyama et al., 1973;Takagaki et al., 1991) probably acting as artificial initiators of glycosaminoglycan elongation givi...

Human Homolog of Caenorhabditis elegans sqv-3 Gene Is Galactosyltransferase I Involved in the Biosynthesis of the Glycosaminoglycan-Protein Linkage Region of Proteoglycans

“…By irradiation at Gal H-1, strong NOEs were observed at Xyl H-4, Gal H-3, and Gal H-5, and also, by irradiation at Xyl H-4, Gal H-1 was strongly enhanced. Thus, the structure of the product was identified as Gal␤1-4Xyl␤1-p-Nph (28).…”

Two Trans-sialidase Forms with Different Sialic Acid Transfer and Sialidase Activities from Trypanosoma congolense

“…That is, TS is a unique enzyme that, because of its ability to transfer Neu5Ac in a stereo-and regio-specific manner, can be utilized to synthesize a variety of biologically relevant structures of the type Neu5Ac␣2,3Gal␤1-R (13,14).…”

Regiospecific glycosidase‐assisted synthesis of lacto‐N‐biose I (Galβ1–3GlcNAc) and 3′‐sialyl‐lacto‐N‐biose I (NeuAcα2–3Galβ1–3GlcNAc)

“…The ability to control both regioselectivity and yield of transglycosylation reactions by varying pH and/or temperature [21,22] or by changing the structure of the acceptors or of the donors [15,16,24,31,32] is well established. It was decided to perform a preliminary survey of the effect of the pH on the rate, yield and regioselectivity of the transglycosylation reaction catalyzed by X. manihotis β‐ d ‐galactosidase (Fig.…”

“…From a practical point of view, the use of glycosidases for transglycosylation reactions is more interesting. They are versatile, and changing various experimental parameters [15–24] can modulate their synthetic activities.…”