Synthesis of O-[2-deoxy-2-[(3R)-3-hydroxytetradecanamido]-beta-D- glucopyranosyl 4-phosphate]-(1 leads to 6)-2-deoxy-2-[(3R)-3- hydroxytetradecanamido]-D-glucose. The monosaccharide route

Synthesis and purification by HPLC of des-O-acyl partial structures of Escherichia coli Re lipopolysaccharide

Four compounds corresponding to partial structures of Re-type lipopolysaccharide (LPS) were synthesized for precise investigation of immunological properties of the 3-deoxy-D- manno-2-octulosonic acid (Kdo)-containing inner core and lipid A regions of LPS. The synthetic compounds lack all the ester-bound acyl groups which are present in natural LPS but known to be not essential for the antigenicity. The simplest compound is N,N'-diacylated glucosamine β1-6 disaccharide 4'-monophosphate 2 which corresponds to the des- O-acyl derivative of 1-dephospho lipid A. The other three contain one or two Kdo moieties linked to 2. The most complex one is a tetrasaccharide equivalent to the des- O-acylated 1-dephosphorylated derivative of LPS from Escherichia coli Re-mutant. Syntheses were performed by stepwise condensation of appropriately protected sugar moieties and final hydrogenolytic deprotection. The synthetic des- O-acyl LPS analogs were effectively purified by means of reversed phase HPLC to give homogeneous preparations.

Strategy for the fine characterization of glycosyltransferase specificity using isotopomer assembly

Glycosylation, which represents the most complex posttranslational modification (PTM) event during protein maturation, has a vital role in biological processes. Glycan biosynthesis is orchestrated by numerous glycosyltransferases, each displaying different selectivities for multiple reaction sites. The precise specificities of these enzymes have been difficult to study because of the lack of available substrates of defined structure and problems associated with the analyses. Moreover, the analysis of glycans is extremely difficult owing to the structural complexity of the glycan chain. Here we describe a new strategy for the fine characterization of enzyme specificity using substrate isotopomer assemblies. Because isotopomer assemblies contain a sugar residue that is position-specifically labeled with a stable isotope, we can use tandem mass spectrometry (MS/MS) to assign the structure of positional isomers generated by glycosylation. We demonstrated the analysis of substrate specificities of five beta4-galactosyltransferases (beta4GalT-I, -II, -III, -IV and -V) using our strategy.

Synthesis of 2-deoxy-4-O-phosphono-3-O-tetradecanoyl-2-[(3R)- and (3S)-3-tetradecanoyloxytetradecanamido]-D-glucose: a diastereoisomeric pair of 4-O-phosphono-D-glucosamine derivatives (GLA-27) related to bacterial lipid A

The diastereoisomeric, 4-O-phosphono-D-glucosamine derivatives named in the title have been synthesized, starting from benzyl 2-amino-2-deoxy-4,6-O-isopropylidene-beta-D-glucopyranoside and (3RS)-3-hydroxytetradecanoic acid.