The effect of galactose side units and mannan chain length on the macromolecular characteristics of galactomannans

The degree of substitution and the degree of polymerization of galactomannan from guar were altered enzymatically to study the role of side groups and chain length in the behavior of molecules in solution. Unmodified guar galactomannan was found to contain aggregates, but partial removal of galactose side units significantly decreased this tendency. The chain length seemed to dictate the solubility of the molecules together with the degree of substitution. The sample with a relatively low degree of polymerization and low degree of substitution formed large assemblies but stayed in solution while the solubility of the samples with longer chain length was reduced. To our knowledge, this is the first report on the utilization of endo-1,4-β-d-mannanase and α-d-galactosidase as tools for studying the solution properties of galactomannans.