Affinity Chromatography of the Major Seed Protein of the Bean (Phaseolus vulgaris L.)

The major globulin of the French bean (Phaseolus vulgaris L.) undergoes a reversible pH-dependent polymerization. At pH values above 6.5, the monomeric form of the protein predominates; and at pH values below 6.5, the protein occurs as a polymer, probably a tetramer. At extremes of pH, the protein dissociates further into peptides. The reversible pH-dependent interaction between globulin subunits is used in this report as the basis for an affinity chromatography procedure for isolation of the globulin. The major globulin from several genetic variants can be obtained in gram quantities and does not indicate the presence of any impurities on discontinuous sodium dodecyl sulfate gel electrophoresis.