Formula-Trisaccharide-Yield-Polymer-Support-Glycosyl-Phosphates-Linker-Reveal-Glycoside-t

Heptasaccharide 33 was prepared in 9% yield in 14 steps.Glycosylation of internal sugar residues of oligosaccharides catalyzed by alpha-galactosidase from Aspergillus fumigatus.Purified alpha-galactosidase from a thermotolerant fungus Aspergillus fumigatus IMI 3858 was found to catalyze efficiently transgalactosylation reactions using 4-nitrophenyl alpha-D-galactopyranoside as glycosyl donor. 2'-Fucose lactose -transfer reactions with this substrate afforded in low yields several 4-nitrophenyl galactobiosides. Monosaccharides also served as poor glycosyl acceptors. Disaccharides and particularly higher oligosaccharides of alpha-1,4-gluco- beta-1,4-manno-series were efficiently galactosylated, the latter being the best acceptors that were also doubly galactosylated.

With mannooligosaccharides product yields increased with polymerization degree of acceptors reaching % at DP of 4-6. Longer oligosaccharide acceptors were galactosylated at internal sugar residues. All galactosyl residues were transferred exclusively to the primary hydroxyl group(s) at C-6 position of oligosaccharide acceptors. This is in accordance with the inability of the enzyme to transfer galactose to beta-1,4-linked xylooligosaccharides. 2'-Fucose lactose is the first report of glycosyl transfer reaction to internal sugar residues of oligosaccharides catalyzed by a glycosidase. High affinity to oligosaccharide acceptors also opens a way toward enzymatic glycosylation of polysaccharides, thus modulating their physico-chemical and biological properties.Regeneration of PAPS for the enzymatic synthesis of sulfated oligosaccharides.

Scripps Research Institute, 5 North Torrey Pines Road, La Jolla, California This paper describes the study of 3'-phosphoadenosine-5'-phosphosulfate (PAPS) regeneration from 3'-phosphoadenosine-5'-phosphate (PAP) for use in practical syntheses of carbohydrate sulfates which are catalyzed by sulfotransferases. Among the regeneration systems, the one with recombinant aryl sulfotransferase proved to be the most practical. This regeneration system was coupled with a sulfotransferase-catalyzed reaction, using a recombinant Nod factor sulfotransferase, for the synthesis of various oligosaccharide sulfates that were further glycosylated using glycosyltransferases.The Endo-α(1,3)-Fucoidanase Mef2 Releases Uniquely Branched Oligosaccharides Tran VHN(1)(2), Nguyen TT(1)(2), Meier S(3), Holck J(1), Cao HTT(2), Van TTT(2), Bioengineering-Department of Biotechnology and Biomedicine, Technical University of Denmark, 20 Kongens Lyngby, Denmark.Science and Technology,2 Hung Vuong Street, Nhatrang 60, Vietnam.Fucoidans are complex bioactive sulfated fucosyl-polysaccharides primarily found in brown macroalgae. Endo-fucoidanases catalyze the specific hydrolysis of α-L-fucosyl linkages in fucoidans and can be utilized to tailor-make fucoidan oligosaccharides and elucidate new structural details of fucoidans.

In this study, an endo-α(1,3)-fucoidanase encoding gene, Mef2, from the marine bacterium Muricauda eckloniae, was cloned, and the Mef2 protein was functionally characterized. Based on the primary sequence, Mef2 was suggested to belong to the glycosyl hydrolase family 7 (GH7) in the Carbohydrate Active enZyme database (CAZy). The Mef2 fucoidanase showed maximal activity at pH 8 and 35 °C, although it could tolerate temperatures up to °C. Ca2+ was shown to increase the melting temperature from 38 to 44 °C and was furthermore required for optimal activity of Mef2. The substrate specificity of Mef2 was investigated, and Fourier transform infrared spectroscopy (FTIR) was used to determine the enzymatic activity (Units per μM enzyme UfμM) of Mef2 on two structurally different fucoidans, showing an activity of 1 × -3 UfμM and 3 × -3 UfμM on fucoidans from Fucus evanescens and Saccharina latissima, respectively. Interestingly, Mef2 was identified as the first described fucoidanase active on fucoidans from S. latissima.

The fucoidan oligosaccharides released by Mef2 consisted of a backbone of α(1,3)-linked fucosyl residues with unique and novel α(1,4)-linked fucosyl branches, not previously identified in fucoidans from S. Conflict of interest statement The authors declare no conflict of interest.Chemoenzymatic synthesis of α2-3-sialylated carbohydrate epitopes.Sialic acids are common terminal carbohydrates on cell surface. Together with internal carbohydrate structures, they play important roles in many physiological and pathological processes. In order to obtain α2-3-sialylated oligosaccharides, a highly efficient one-pot three-enzyme synthetic approach was applied. The P.