THE MOLECULAR CHARACTERIZATION OF THE POLYSACCHARIDE GUM FROM ACACIA-SENEGAL

Gum arabic (Acacia senegal gum) was fractionated by hydrophobic intera ction chromatography on Phenyl-Sepharose CL-4B and yielded four fracti ons of similar carbohydrate composition, whilst differing in protein c ontent, amino acid composition, and molecular mass distribution. All f our fractions interacted with an array of anti-arabinogalactan-protein (AGP) monoclonal antibodies via anti-carbohydrate epitopes and were p recipitated by Yariv's reagent, suggesting that they were all AGPs. Fu rther characterisation using SDS-PAGE and Western blotting showed that all fractions contained proteins of molecular mass 30000-45000 with a t least one protein unique to each fraction. The fractions were subjec ted to enzymatic (with pronase) and alkaline hydrolysis, and the molec ular mass distribution of the products was monitored by gel permeation chromatography. The fractions showed various degrees of resistance to hydrolysis, thus illustrating differences in their macromolecular str ucture.