Glucomannans yeast

In addition to chitin (O Sect. 2.2), yeast cell walls may contain a (1 3)- -glucan, a (1 6)- -glucan, various mannans, or a galactan. Other cell-wall components of certain fungi are rhamnomannans, glucomannans, galactomannans, xylomannans, glucuronoxylomannans, and other polysaccharides [42]. 

Some activity is seen with certain D-mannans and glucomannans (see Table VIII). Fragments of yeast mannans showed some activity, and the fractions of highest molecular weight were the most active.195... 

Periodate-oxidized yeast glucomannan is found" to enhance the thermal stability of the levansucrase of B. natto, perhaps due to an intermolecular association between the polymer and the enzyme. 

Y. Ben Ammar, T. Matsubara, K. Ito, M. Bzuka, and N. Minamiura, Some properties of levansucrase of Bacillus natto stabilized with periodate oxidized yeast glucomannan. Enzyme Microbiol. Tech., 30 (2002) 875-882. 

Table IV lists those yeasts (other than the aforementioned Sporobolomyces sp.) that synthesize polysaccharide-like 0 -phos-phonoglycans along with the various a-g-glycose 1-phosphate end groups found thus far (50). A new aspect of the phosphomannan story is introduced in this table When grown in the absence of added orthophosphate, almost all such yeasts alternatively synthesize neutral a-D-mannans and glucoraannans. Common biogenetic origin of the neutral and phosphorylated mannans and glucomannans is evidenced by similar amounts of g-glucose or its absence in the biopolymers produced by a given strain of yeast.

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. 

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

D. Chorvatovicova, E. Machova, J. Sandula, G. Kogan, Protective effect of the yeast glucomannan against cyclophosphamide-induced mutagenicity, Mutofion Res., 444,117-122,1999. 

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