A method of stepwise chemical degradation was elaborated on a μg quantity of 3-O-α-l-fucosyllactose. The key step, TiCl4-catalysed dithioacetal formation from the permethylated N-4-nitrophenyl triosylamine (4) was accompanied by quantitative defucosylation. [14C]Acetylation of the dried mercaptalation mixture gave radiolabelled 3,5-di-O-[14C]acetyl-4-O-(2,3,4,6-tetra-O-methyl-β -d-galactopyranosyl)-2,6-di-O-methyl-d-glucose diethyl dithioacetal (7) and 5-O-[14C]acetyl-2,3,4-tri-O-methyl-l-fucose diethyl dithioacetal (8). The former was further degraded via the bis(sulfone), and thereby 2,3,4,6-tetra-O-methyl-d-galactose (13) was expelled. The monosaccharide branches, fucose and galactose, were identified as derivatives 8 and 13, respectively, by comparison with authentic samples. Isolation of microquantities of products was carried out by preparative TLC.

Starting from pentaerythritol, photolabile mono-, di-, and tri-dentate galactose derivatives as well as their 3H-labelled isotopomers were synthesised. The hydrophilic chains linking the 6 position of D-galactose to pentaerythritol consist of 13 atoms in line. The mono-, di- and tri-dentate compounds, although themselves not transported, inhibit in increasing order 14C-D-galactose transport into erythrocytes. On irradiating whole cells in the presence of ligand with 350-nm UV light, these compounds also in increasing order, could irreversibly block the hexose transport system. Irradiation without ligand has no effect. By using the 3H-labelled tridentate galactose compound the hexose transporter (zone 4.5) is specifically radiolabelled, as could be shown in an SDS-PAGE of membrane proteins from erythrocytes previously photoaffinity labelled. Radiolabelling is significantly suppressed in the presence of D-glucose.

Glass high-resolution TLC plates were used to separate very small amounts of material (ng-mg). Either spots or linear zones can be quantitatively eluted after separating them from the surroundings with a fast-moving drill, which removes thin lines of layer material. Elution is carried out by siphoning eluent through a specially formed sintered glass on to one end of the zone or spot and picking up the eluate at the other with a piece of filter-paper carton. The latter can be extracted by soaking and centrifugation. Application in the carbohydrate field is demonstrated by a preparative isolation for structural analysis of three components and the determination of different amounts of one compound for analytical purposes.

1,3-Diamino-1,3-dideoxy-d-threitol (1) and the corresponding 1,3-diamino-1,3-dideoxy-d-erythritol (2) were synthesised starting from d-glucose and l-arabinose, respectively. These acyclic diamines inhibited competitively both β-d-glucosidase from sweet almond emulsin and β-d-galactosidase from E. coli with Ki-values ranging from 3 to 10 mM. When the suitably blocked diamines were reacted with activated carbonic and thiocarbonic acid derivatives, cyclic urea 5(R)-hydroxy-4(R)-hydroxymethyl-tetrahydropyrimidin-2-one (13), 5(S)-hydroxy-4(R)-hydroxymethyl-tetrahydropyrimidin-2-one (15) and thiourea 5(S)-hydroxy-4(R)-hydroxymethyl-tetrahydropyrimidin-2-thione (18) derivatives were obtained, which conformationally resemble the envelope structure of the d-glucopyranosyl or the d-galactopyranosyl cation. The cyclic carbonamides showed extremely weak competitive inhibition but only with their corresponding enzymes. Compounds 15 and 18 exist, as indicated by 1H NMR spectroscopy, in an unexpected E-conformation with axial substituents. Upon per-O-acetylation the expected conformation with equatorial substituents is adopted.

The spacer-modified trisaccharides that mimic (1→6)-linked β-d-galactotetraose (Gal4), namely, O-β-d-galactopyranosyl-(1→6)-S-β-d-galactopyranosyl-(1→11)-8-azi-6,7,8,9,10-pentadeoxy-11-thio-d-galacto-undecose (12) and O-β-d-galactopyranosyl-(1→6)-O-β-d-galactopyranosyl-(1→3)-8-azi-6,7,8,9,10,11,12-heptadeoxy-d-galacto- tridecose (20) were synthesised by coupling disaccharide derivatives with 8-azi-6,7,8,9,10-pentadeoxy-1,2:3,4-di-O-isopropylidene-11-O-tosyl-α-d-galacto-undecopyranose (10) and 8-azi-6,7,8,9,10,11,12-heptadeoxy-1,2:3,4-di-O-isopropylidene-α-d-galacto-tridecopyranose (17), respectively. Compounds 12 and 20 had affinities for the combining sites of the antibodies IgA X 24 and IgA J 539 similar to those of O-β-d-galactopyranosyl-(1→6)-O-β-d-galactopyranosyl-(1→11)-8-azi-6,7,8,9,10-pentadeoxy-d-galacto- undecose (7) and the native ligand Gal4. Tritium-labelled 7 chemically modified the heavy and light chains of IgA J 539, whereas 8-azi-6,7,8,9,10-pentadeoxy-d-(11-3H)galacto-undecose (5a) reacted only with the heavy chain.

AbstractThe potential photoaffinity reagent (VIII) is prepared starting from the D‐galactohexodialdopyranose (I) via twofold chain elongation and subsequent modifications of the alkyl chain.

AbstractHigh affinity for the four‐center binding site of a monoclonal antibody is a feature of the spacer‐modified trisaccharide (I) (synthesis described).