Mannan-Containing Polysaccharides

Mannan-contalning polysaccharides are foxmd ubiquitously in yeasts and fungi in various forms, including phosphomannans, galactomannans, glucomannans. 

---

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... 

Several studies concerning D-mannosyl transfer from GDP-Man and Man-p-Pre onto unidentified acceptors in Mycobacteria have been published.67,393 The enzymic system may use methyl a-D-mannopyranoside as the exogenous acceptor for D-mannosyl transfer.394 In this case, formation of a-(l- 2) linkages was observed they are present in 3-O-methyl-D-mannose-containing polysaccharides and a D-arabino-D-mannan characteristic of mycobacterial cell-wall. 

Hess and coworkers53 have isolated mannose-containing polysaccharides from both ivory nuts and from pine wood pulp, and these mannans appeared to have identical properties. Both gave specific rotations of approximately —45° in N sodium hydroxide and +285° in cuprammonium (0.04 mole hexose anhydride, 0.10 mole copper, 10.0 moles ammonia per liter). The exact composition of these polysaccharides is not known Yundt54 has recently stated that mannan A from ivory nuts assayed only 50 percent mannose. The cuprammonium rotation data cannot be interpreted in terms of the fine structure until the composition of the mannans is known with certainty. 

Hansenula holstii NCYC 560 produces cell-wall, and exocellular, phosphorylated mannans of mol. wt. 10°. The cell-wall mannan contains two branched polysaccharides having (l- 2) and (1— 3) linkages, with /3-d, in addition to a-D, linkages. Phosphoric diesters are present. The exocellular phosphonomannan is composed of 3 polymers, each... 

Such H-1 signals can be used as a fingerprint using known mannans as references (Table I) in order to identify parent yeasts isolated from rivers and lakes. This is aided by the versatility of yeasts in producing mannose-containing polysaccharides of different chemical structure (2)- In cases where spectra cannot be obtained the component sugars can sometimes be used to define the polysaccharide., ... 

Figure 5. Partial NMR spectra of galactofuranose-containing polysaccharides in (A) glucomannan and mannan from Ceratocystis paradoxa and (B) gluco-mannan from Ceratocystis brunnea...

Konjac mannan contains acetate residues linked to the polysaccharide by ester bonds. One acetate group is present for every 19 residues of D-mannose and acetic acid is the only acid present. A series of water-soluble methylated glucomannans from Konjac have been prepared. The polysaccharides with the maximum viscosity had a degree of substitution of 0.45. 

Methylation of a polysaccharide containing 2-amino-2-deoxy-D-galactose (88 %), protein (6.8 %), and phosphate (4.7 %) has indicated a linear structure of (1 — 4)-linked amino-sugar residues. An L-rhamno-D-mannan containing single unit a-L-rhamnopyranosyl side chains has been identified in isolated conidia of Sporothrix schenckii and differs from the di-L-rhamnosyl-D-mannan synthesized by the hyphae. ... 

On the basis of the n.m.r. spectra, various structural assignments have been made to polysaccharides of S. schenkii, including a neutral mono-L-rhamnosyl-D-mannan and an acidic L-rhamno-D-mannan. Many strains from species of Sporothrix, Ceratocystis, Europhium, and Graphium have exhibited serological cross-reactions with S. schenckii, and contain polysaccharides composed of residues of L-rhamnose and D-mannose. The d-galacto-D-mannan of Schizosaccharomyces pombe has been located at the periphery of the cell wall and near the plasmalemma. No evidence was obtained for the presence of chitin. 

The middle lamella or intercellular layer contains cellulose, xylans, uronic acid - containing polysaccharides, and sometimes a mannan. Poly-... 

The primary wall is a continuous, fairly pliable membrane forming the outside surface of the plant cell. It is about 0.5 micron in thickness and, thus, is only a small part of the cell. It is heavily lignified but is predominantly carbohydrate, with pectin, uronic acid - containing polysaccharides, and xylan or mannan in abundance and with cellulose in lesser amounts. For the most part the very long cellulose molecules are grouped into many fine threads (Fig. 3) which form a meshlike but coherent arrangement. They are intricately woven and mixed with the other polysaccharides,... 

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. 

---