Functional improvements in β-conglycinin by preparing bioconjugates with carboxymethyl cellulose

β-Conglycinin was conjugated with carboxymethyl cellulose (CMC) by using water-soluble carbodiimide to improve its function. Two kinds of CMC differing in average molecular weight (about 1 kDa and 90 kDa) were used to investigate the relationship between molecular weight of conjugated saccharide and saccharide content in the conjugates and degree of functional changes in β-conglycinin. The β-conglycinin-CMC conjugates were purified by dialysis using a dialysis membrane whose molecular weight cutoff is 100 kDa. Composition of the β-conglycinin-low molecular weight (LMW) CMC and β-conglycinin-high molecular weight (HMW) CMC was β-conglycinin: CMC = 1:3.3 and 1:2.1 (weight ratio) respectively which was confirmed by BCA method and phenol sulfuric acid method. Conjugation was confirmed by SDS-PAGE with CBB. Solubility of β-conglycinin in the range of pH4.0-7.0 was much improved by conjugation with both LMW and HMW CMC. Emulsifying property of β-conglycinin at pH5.0 and pH7.0 was much improved by conjugation with HMW CMC and greater improvement was achieved by conjugation with LMW CMC. Immunogenicity of β-conglycinin was decreased by conjugation with LMW CMC.