Glucomannans branches

P-D-mannan with single 6-Unked a-D-galactose branches g 4)-p -D-glucomannan ... 

The linear, but highly branched, molecular structure of the galactomannans is the reason for some specific properties which are quite different from those of the unbranched cellulose-like and water-insoluble mannans and glucomannans. Galactomannans are hydrated in cold water and give stable solutions even in acidic formulas. The interactions of galactomannans with other polysaccharides are the base of a variety of industrial applications. 

Inspection of the literature shows that branching is clearly indicated for three glucomannans, and a linear backbone for four. It should, however, be noted that the evidence obtained by this method is far more equivocal when no branching is indicated, because part of the volatile glycosides of tetra-O-methyl-D-glucose and -n-mannose is readily lost, whereas their presence in an excess of that required by a linear structure could scarcely be ascribed to any experimental ambiguity. 

It is clear that chemical evidence is, at present, available both for and against a branched framework in softwood glucomannans. It was mentioned (Part I, p. 286) that (4-0-methylglucurono)xylans and cellulose apparently occupy a similar hydrodynamic volume in solution. In view of this fact, it appears fairly safe to assume that the same should apply to the glucomannans, which are structurally much closer to cellulose than... 

Mannan from thickened cell walls of palm seeds yeast is d-Manp in 3-l- 4 and side chain at 3-l->6. Glucomannan from tuber consists of Glc and Man. Man is a constituent of oligosaccharides of iV-glycoproteins in a-1—>2, al 3 and al—>6 (as branching points) and 31—>4 (main) linkages. Man is attached to serine in 0-glycoproteins. 

Maeda, M., Shimahara, H., and Sugiyama, N., Detailed examination of the branched strncture of konjac glucomannan, Agric. Biol Chem., 44, 245,1980. 

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