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O -Glycosylation

The same glycosylation was extended to D-galactose, o-mannose, and N-troc-o-glucosamine with similar results. The same authors also achieved glycosylation of [Pg.589]

By means of an ETHOS MR oven, Nuchter et al. [33] accomplished scaling-up of a microwave-assisted Fischer glycosylation to the kilogram scale with improved economic efficiency. In batch reactions, carbohydrates (o-glucose, o-mannose, d-galactose, butyl o-galactose, starch) were converted on the 50-g scale (95-100% yield, from 95 5 to 100%) with 3-30-fold molar excesses of an alcohol (methanol, ethanol, butanol, octanol) in the presence of a catalytic amount of acetyl chloride under pressure (microwave flow reactor, 120-140 °C, 12-16 bar, 5-12 min) or without applying pressure (120-140 °C or reflux temperature, 20-60 min). Furano-sides are not stable under these reaction conditions. [Pg.590]

Seibel et al. [36] reported, for the first time, the use of microwave heating in the glycosylation of amino acids. They performed glycosyl transfer reactions of perace-tylated monosaccharides (glucose and galactose) and disaccharides (maltose and lactose) with N-9-fluorenylmethoxycarbonyl-L-serine benzyl ester in the presence of iron trichloride with short reaction times (4 min, compared with 5-10 h by conventional heating) and with improved yields (52-61% compared with 10-31% by conventional heating). It is worthy of note that in these reactions heavy metal compounds, for example silver trifluoromethanesulfonate, mercury dibromide and di-cyanide, or boron trifluoride-diethyl etherate, can be replaced by the environmentally safe promoter iron trichloride. [Pg.590]

O-Glycosylation via Perrier s rearrangement [39], an allylic rearrangement of gly-cals (1,2-unsaturated pyranosides) in the presence of nucleophiles, has acquired great significance in carbohydrate chemistry, because of the further transformation of the products into other interesting carbohydrates [40]. In addition to affording [Pg.591]

50- R = aryl 51 R = ethyl, cyclohexyl, ally 52 R=W-hydroxymethyl-, W-hydroxyethyl-, (S)-(+)-W-hydroxy-isopropyl-phthalimide, (/ ,S)-2-phenyl-, R,S)-(4-tolyl)-1,2,4-oxadiazol-5-yl-2-bLitanol 53 R = allyl, propargyl, heptyl, benzyl, pent-4-enyi, phenethyl. [Pg.592]


Jentoft, N., 1990. Wliy are proteins O-glycosylated Trends in Biochemical Sciences 155 291-294. [Pg.237]

The diamonds in Fig. 1 represent the point of O-glycosylation by tetrasac-charide 1. Asn-26 indicates the point of N-glycosylation by the complex oligosaccharide 2. [Pg.173]

PGE was isolated as desribed in Material and Methods. SDS-PAGE electrophoresis of purified protein showed a single band migrating at approximately 60 kDa. This observation is not in the agreement with the calculated molecular weight of 35 584. However a similar effect has been observed previously in case of PGI and PGC. Apart of the N-glycosylation which plays role in all PGs (Fig. 3), O-glycosylation may also be present as indicated by the band size shift after a treatment of PGE with O.IM NaOH (data not shown). [Pg.828]

IV. Structural Analysis of Glycopeptides and Glycoproteins Containing O-Glycosyl Linkages... [Pg.21]

Now that the general considerations concerning the 13C-n.m.r.-spec-tral data for O-glycosylated model compounds have been discussed, attention may be focused on some specific cases. Table IV gives the 13C-n.m.r.-spectral data for L-serine that has been glycosylated with various carbohydrates, such as a- and / -d-G1c, a- and /9-D-Gal, a- and / -d-Xyl, a-D-Man, and a-D-GalNAc. As mentioned earlier, the specific resonance-assignments to amino acid carbon atoms were based on chemical... [Pg.25]

As mentioned in the Introduction, a variety of unusual carbohydrate -protein linkages is found in Nature. These may be placed in several categories (i) carbohydrates O-glycosylated to jff-hydroxy amino acids (ii) carbohydrates S-glycosylated to cysteine (Hi) carbohydrates N-gly-cosylated to the N-terminal amino group of the protein or (iv) in some... [Pg.44]


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O-glycosylated

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