Abstract for International Carbohydrate Symposium
Olso, Norway
August 2008
Analysis of Side Chain Lengths of Branched β-1,3-Glucans by Alkaline Degradation
A. Magee1, M. Danielson1, R. Dauth1, T. Stevenson2 and P. Will1
1Biothera, 3388 Mike Collins Drive, Eagan, MN 55121, USA
2Neose Technologies, Inc., 102 Rock Rd., Horsham, PA 19044, USA
The principal polysaccharide component of the cell wall of yeasts and fungi is β-1,3-glucan, branched to varying degrees at the 6-position. β-1,3-Glucan obtained from various sources has been known to affect immune response in both in vitro and in vivo systems for
some time. As a result, β-1,3-glucan has been studied as a therapeutic agent in anti-infective
and anti-cancer indications. However, the results from many of these studies are difficult to
interpret as the structure, as well as the purity, of the glucans used in each study has often
been incompletely defined. Structural variations that may effect bioactivity such as
molecular weight and percent branching of β-1,3-glucans can be determined by relatively standard methods. The distributions of different lengths of side chains on the polysaccharide
main chain is potentially another important structural feature. An analytical method to
address this feature is described. As a 3-linked polysaccharide, β-1,3-glucan in alkali undergoes a beta elimination reaction, or “peeling” reaction, that fragments the main chain
starting at the reducing end while releasing the 6-linked side chains. The released side chains
undergo a rearrangement to meta-saccharinic acid derivatives1. These side chain derivatives
are separated by preparative gel permeation chromatography and characterized to confirm
their identity. For analytical purposes, the meta-saccharinic acid derivatives are separated by
High Performance Anion Exchange Chromatography (HP-AEC) with detection by Pulsed Amperometric Detection (PAD) to quantitate the relative amounts of different length side
chains. This analytical method is applied to β-1,3-glucan derived from various yeast species as well as other sources to compare the relative distributions of branch chain lengths.
[1] G.O. Aspinall, T.N. Krishnamurthy, I. Furda and R. Khan, Can. J. Chem., 53, 2171
(1975).