Polymannose

The melt polymerizations of 1,2,3,4-tetra-0-acetyl-j3-D-mannose and -D-galactose in the presence of zinc chloride have been described.152 Chemical investigation of the structure of the polymannose suggested that it is mainly an a-D-( 1—+6)-linked polymer having a Pm of 10. In the same way, 1,2,3,4-tetra-O-acetyl-n-gaIactose was polymerized. 

Polymerization of 1,6-anhydro-/3-D-mannopyranose by means of monochloroacetic acid, using the conditions of Schuerch and coworkers,24 218 has also been accomplished,218 to give a polymannose in 25% yield. This polymer appears to be highly ramified and to contain a high proportion of terminal, nonreducing a-D-mannopyranosyl groups as determined by the precipitation reaction with concanavalin A (see Section IV,6). 

Other methods of fractionation which utilize the presence of ionizable groups, either natural (such as carboxyl or amino groups), or induced (such as borate complexes), may be useful. Such methods have been discussed in reviews.248 2W Complexation (for example, with Fehling solution) was found useful in the study of a polymannose.216 An insoluble complex was formed, as with natural mannans. 

R. G., Role of A-linked polymannose oligosaccharides in targeting glycoproteins for endoplasmic reticulum-associated degradation. Cell. Mol. Life Sci. 61,1025-1041, 2004 Bedard, K., Szabo, E., Michalak, M., and Opas, M., Cellular functions of endoplasmic reticulum chaperones calreticulin, calnexin, andERp57, Int. Rev. Cytol. 245, 91-121, 2005 Ito, Y, Hagihara,... 

Lefkowitz SS, Lefkowitz DL (1999) Macrophage candidicidal activity of a complete glyconu-tritional formulation verses aloe polymannose. Proc Fisher Inst Med Res 1 5-7... 

Saint-Pol, A., Codogno, P., and Moore, S. E. H. (1999). Cytosol-to-lysosome transport of free polymannose-type oligosaccharides. Kinetic and specificity studies using rat liver lysosomes. J Biol. Chem. 274, 13547-13555. 

Bottom panel. Untreated RAW cells contain mainly polymannose M4N1 and M5N1 solid... 

Figure 3-18 Chemical structure of acetylated polymannose (Acemannan )...

A more interesting enzymatic modification, from an economical point of view, is treatment of guar gum with a-galactosidase. En matic removal of part of the galactose side-groups results in stretches of unsubstituted polymannose backbone. In this way a polysaccharide is obtained which is similar to locust bean gum, which currently is 15-times more expensive than guar gum. 

Another aspect that we have not yet looked into is the possibility of further tailoring the properties of oxidized guar by using a-galactosidase to create stretches of unsubstituted polymannose backbone which might have an impact on the interaction of the modified oxidized guar with cellulose. 

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