Microbial exopolysaccharides - Structural subtleties and their consequences

Abstract

Microbial extracellular heteropolysaccharides are mainly linear molecules to which side chains of varying length and complexity are attached at regular intervals. Examination of 'families' of microbial exopolysaccharide with closely related structures enables us to determine the effect of minor (or major) changes to structure on the physical properties of these macromolecules. Changes may also be seen in some of the biological properties of the polysaccharides, such as susceptibility to enzymes; interaction with antibodies or lectins; and capacity and specificity of ion binding. Acetyl groups frequently assert very marked effects on the properties of microbial polysaccharides. The presence or absence of an O-acetyl or pyruvate (ketal) group on each oligosaccharide repeat unit can greatly alter the properties of a number of exopolysaccharides.