Linked Galactose Residues Research Articles

N-Acetyl-D-galactosamine-inhibitable adherence lectin of Entamoeba histolytica. II. Mitogenic activity for human lymphocytes.

A soluble protein preparation from virulent axenic amoebae (strain HM1-IMSS) has been demonstrated to be mitogenic for normal human lymphocytes; mitogenesis was optimal at 100 micrograms/ml when incubation was maintained for five to seven days with monocytes (P less than .001). After gel filtration chromatography mitogenic activity of fractions was associated with N-acetyl-D-galactosamine-inhibitable lectin activity (agglutination of Chinese hamster ovary cells; P less than .001). Lymphocyte proliferation induced by these active fractions was specifically inhibited by asialofetuin (P less than .001), which contains three terminal beta 1-4 linked galactose residues. In four strains of axenic amoebae mitogenic activity of soluble protein preparations correlated with in vitro virulence and lectin activity for Chinese hamster ovary cells. The amoebic N-acetyl-D-galactosamine-inhibitable lectin appears to be responsible for the mitogenic activity of soluble amoebic protein preparations; alteration of cell-mediated immunity by this amoebic moiety could potentiate in vivo virulence of the parasite.

Arabinogalactans in a purified allergen preparation from pollen of timothy ( Phleum pratense)

The purified allergen preparation representing a certain fraction of an aqueous timothy pollen extractcontained ca. 20% carbohydrate, mainly as arabinose (7%) and galactose (13%). The protein content was 63%. Fractionation on DEAE-Sephadex and Sephadex G-100 gave one neutral and two acidic fractions, all containing protein, arabinose and galactose. The structure of the carbohydrate moiety was investigated by methylation analysis, periodate oxidation and enzyme incubation. The acidic fraction contained (1→6)-linked galactose residues, some being substituted on O-3 with arabinose. The neutral fraction consisted of a more extensively branched arabinogalactan with longer side chains of (1→3)- and (1→5)-linked arabinose. The arabinose was present mainly as α- l-arabinofuranosyl residues. Alkaline degradation and subsequent fractionation indicated the presence of a covalent linkage between hydroxyproline and arabinose. Periodate oxidation or incubation with α- l-arabinofuranosidase did not affect the allergenic activity of the extract.

The structure of the polysaccharide of Pachymenia carnosa

The sulphated polysaccharide of Pachymenia carnosa and its desulphated derivative have been studied by methylation analysis. Depolymerization during the desulphation process has been shown to occur mainly through the cleavage of (1→3) linkages. The methylation results indicate that the ratio of (1→4) to (1→3) linkages in the native polysaccharide is 1:2.26. The sulphate groups occur on positions 2, 4, and 2,6 of (1→3)-linked galactose residues. Methylations carried out in methyl sulphoxide with the Purdie reagents lead to extensive desulphation; 2-sulphate units appear to be more susceptible to desulphation than 4- or 6-sulphate units. Desulphation does not occur during methylation by the Hakomori method.

Analytical and structural features of the gum exudate from Combretum hartmannianum schweinf.

The gum exudate from Combretum hartmannianum is water-soluble, forms very viscous solutions, and contains galactose (22%), arabinose (43%), mannose (10%), xylose (6%), rhamnose (4%), glucuronic acid (6%), 4- O-methylglucuronic acid (2%), and galacturonic acid (7%). The acidic components produced on hydrolysis of the gum were 6- O-(β- D-glucopyranosyluronic acid)- D-galactose, and two saccharides that had the same chromatographic mobility, and contained mannose and galacturonic acid, and galactose and 4- O-methylglucuronic acid, respectively. Methylation and methanolysis of the gum indicated the presence of terminal uronic acid, rhamnose, xylose, galactose, arabinofuranose, and arabinopyranose. Controlled, acid hydrolysis indicated the presence of (1→3)-linked arabinopyranose side-chains and (1→6)-linked galactose residues. C. hartmannianum gum, when subjected to two Smith-degradations, yielded Polysaccharides I and II, both of which contained galactose, arabinose, and mannose. Insufficient crude gum was available for a complete structural study, but the molecule was shown to contain long, sparsely branched chains of (1→6)-linked galactose residues, to which are attached (1→3)-linked arabinose and (1→3)-linked mannose side-chains.

Carrageenans: Part V. The masked repeating structures of λ- and μ-carrageenans

For the potassium chloride-soluble fractions of five carrageenans, correlations have been established between 3,6-anhydrogalactose content and the products of methylation and fragmentation. After modification with alkaline borohydride, two subtractions were obtained, and shown to be distinct by methylation analysis and other methods. Carrageenan is now believed to contain three polysaccharide components: ϰ-carrageenan, λ-carrageenan, and μ-carrageenan. All have masked repeating structures based on alternately (1→3)- and (1→4)-linked galactose residues, but there are important differences in sulphation pattern and 3,6-anhydride content.

CHOLLA GUM: II. STRUCTURE OF THE UNDEGRADED CHOLLA GUM

Cholla gum (Opuntiafulgida) has partially been degraded to yield several oligosaccharides and a degraded polymer. The structure of the degraded polymer was reported in an earlier paper. Six of the oligosaccharides formed have been isolated in a pure state and identified. They are (i) 6-O-β-D-galactopyranosyl-D-galactose, (ii) 3-O-β-D-galactopyranosyl-D-galactose, (iii) 3-O-α-L-arabinofuranosyl-L-arabinose, (iv) 5-O-β-D-xylopyranosyl-L-arabinose, (v) 3-O-β-D-galactopyranosyl-L-arabinose (?), and (vi) a new trisaccharide O-β-D-xylopyranosyl-(1 → 5)-O-α-L-arabinofuranosyl-(1 → 3)-L-arabinose. The purified gum was subjected to Smith-type degradation, and the results of this experiment are compared with the methylation studies carried out earlier. On the basis of all this information plus the suggested structure for the degraded gum, it is proposed that the repeating unit of the polysaccharide consists of a total of 36 sugar residues with a backbone of 1 → 6 linked galactose residues.