Polysaccharides mannan

The 08- and 09-specific lipopolysaccharides of Escherichia coli lose their serological activity upon mild acid treatment to liberate their polysaccharide (mannan) moieties.Restoration of the activity was achieved by substitution of one or two stearoyl groups per polysaccharide chain. The D-mannans obtained by in vitro biosynthesis were serologically active only when bound to the membrane-associated hydrophobic carrier. 

Many different types of carbohydrate-containing molecules are located on the surface of microbial cells. Some of these are components of die microbial cell wall and are limited to certain types of micro-organisms such as bacterial peptidoglycan, lipopolysaccharides, techoic adds and yeast mannans. Other polysaccharides are not... 

Mannans (Tagut Nut, Corajo, Vegetable Ivory, Carobean), (CgHioOg, mw 162.14. Poly-, meric polysaccharides which yield mannose on hydrolysis. They can be acetylated and nitrated... 

The mannan-type polysaccharides of higher plants can be divided into... 

During the past decade, MALDI-TOF MS has proven to be an effective tool for the analysis of oligo- and polymeric mannoglucans (for extensive reviews see [222,223]). SEC/MALDI mass spectrometry was employed in the analysis of hemicelluloses isolated by microwave heat-fractionation from spruce and aspen wood [94]. These methods allowed the separation and characterization of the oligo- and polysaccharide fractions derived from the xylan and mannan components of both woods [224]. 

It is often difficult to compare the various mannan-type polysaccharides with regard to their molecular weight, because of the different analytical techniques used. Nevertheless, the Mw values reported for the GM and GGM isolated from woody tissues are rather low (1600 to 64000g/mol) [197-199, 216,219,221] in comparison to those of the water-extractable galactoman-... 

Several methylated sugars have been identified in hydrolyzates of LPS, cell-wall polysaccharides, and extracellular polysaccharides. A considerable number of these have been found in the LPS from photosynthetic prokaryotes. Two polysaccharides from Mycobacterium species, a glucan" and a mannan" are remarkable in that they contain high percentages of methylated sugars. Glycolipids from Mycobacterium species are also rich in methylated sugars, some of which have not been found elsewhere, but this is beyond the scope of the present article. 

At high temperatures, the Tj values of 13C nuclei of polysaccharides may be sufficiently long to create difficulties in quantitative estimation of integral intensities. Values have been observed, at 25.2 MHz, of 0.27-0.31 s [C-l-C-5 of a-D-(l—>6)-linked D-mannopyranan at 90°], and, for side chains of branched-chain mannans, of 0.22 s [C-l of a-D-mannopyranosyl groups linked (1—>2) to a main chain of (1—>6)-linked-D-mannopyranosyl residues at90°] and of 0.31 s [C-l atoms of2-0-sub-stituted /3-D-mannopyranosyl side-chain units linked (1—>2) to a similar main-chain, at 70°]. Under such conditions, the n.O.e. values are57... 

The structure of mannose-rich polysaccharide core in GL4 is close to that of yeast mannan (from Saccharomyces cerevisiae), which was inactive for IL-6 induction in a human peripheral whole-blood cells test system. This fact suggests that not the mannose moieties but other components, such as the lipophilic moiety and/or phosphates, are important for the activity. The lipophilic products in HF-hydrolysate of GL4 were then analyzed. In addition to peaks corresponding to the known fatty acids (C16 0, C18 1), two other unknown ion peaks at m/z 330 and 356 were found by FAB-MS (data not shown). 

Hydrolysis of mannan-type polysaccharides by P-mannanase is dependent on substitution on and within the main-chain as well as the source of the P-mannanase employed. Characterisation of reaction products can be used to define the sub-site binding requirements of the enzymes as well as the fine-structures of the polysaccharides. Action of c/xt/o-arabinanase and em/o-galactanase on arabinans and arabinogalactans is described. Specific assays for ndo-arabinanase and arabinan (in fruit-juice concentrates) are reported. 

The most characterised D-mannan degrading enzymes are the endo- -mannanases (5). These enzymes act on a range of 1,4-p-D-mannan-type polysaccharides including D-mannan, glucomannans (acetylated and deacetylated), galactomannans and galacto-glucomannans. The extent and... 

Assay and Purification of p-Mannanases. p-Mannanase can be specifically measured in crude enzyme mixtures with a dye-labelled carob galactomannan substrate (6), This substrate has a galactose content high enough (23%) to impart solubility to the substrate, but sufficiently low as not to interfere with the action of p-mannanases on the D-mannan backbone. The soluble dye-labelled substrate is incubated with enzyme preparation under controlled conditions and the reaction is terminated and unreacted dyed polysaccharide precipitated by ethanol addition. 

In the present work, we extend the method to compensate for the hydrogen bonds present in carbohydrates. The hydroxylated character of carbohydrate polymers influences between-chain interactions through networks of hydrogen bonds that occur during crystallization. Frequently, several possible attractive interactions exist that lead to different packing arrangements, and several allomorphic crystalline forms have been observed for polysaccharides such as cellulose, chitin, mannan and amylose. The situation is even more complex when water or other guest molecules are present in the crystalline domains. Another complication is that polysaccharide polymorphism includes different helix shapes as well. 

---