Chapter 2.1 - Chemistry of β-Glucans

Abstract

This chapter discusses the chemical characteristics of (1,3)-β-glucans and related polysaccharides that have been structurally defined. The simplest (1,3)-β-glucans are linear, unbranched chains as found in callose, curdlan, paramylon, and pachyman. In the side-chain-branched members, exemplified by the chromistan and fungal laminarins and the fungal mucilage glucans, the (1,3)-β-glucosyl chain residues are substituted to varying degrees at C(O)6 by single β-Glc residues or in some instances by short (1,3)-β-oligoglucosyl chains. The cyclic (1,3)-β-glucan from Bradyrhizobium japonicum is com- posed of two blocks of three (1,3)-linked Glc units separated by two blocks of three (1,6)-linked Glc units, and has a single branch (1,6)-linked Glc residue at C(O)6 of one of the cyclic glucoses. Some molecules are substituted by phosphocholine at C(O)6 on one of the cyclic Glc residues.