Fractionation and characterization of gum from Acacia senegal

Gum from Acacia senegal has been fractionated using hydrophobic affinity chromatography. Characterization, including identification of sugars and determination of protein and amino acid contents, has been undertaken for each fraction together with measurements of molecular mass and molecular mass distribution using laser light scattering and gel permeation chromatography. The results have indicated that the gum consists of three distinct components. Fraction 1. which represents 88.4% of the total, is an arabinogalactan with molecular mass 2.79 x 10(5) and is deficient in protein. Fraction 2, which represents 10.4% of the total. is an arabinogalactan-protein complex with a molecular mass of 1.45 x 10(6), containing similar to 50% of the total protein. It is envisaged that on average each molecule of fraction 2 consists of five carbohydrate blocks of molecular mass similar to 2.8 x 10(5) covalently linked through a chain of amino acid residues. Fraction 3 represents only 1.24% of the total gum but contains similar to 25% of the total protein and has been shown to consist of one or more glyeoproteins. Whereas the proteinaceous components of fractions 1 and 2 contain predominantly hydroxyproline and serine. this is not the case for fraction 3.