Purification and Characterization of Soybean Allergen Gly m Bd 28K

At least 15 allergenic proteins have been found in soybean using the sera of soybean-sensitive patients with atopic dermatitis [T. Ogawa et al., J. Nutr. Sci. Vitaminol., 35, 555–565 (1991)]. In the present study, a monoclonal antibody (mAb) against Gly m Bd 28K, one of the major allergens of soybean, was prepared, and Gly m Bd 28K was purified from defatted soybean flakes by five purification steps, including immunoaffinity chromatography with the mAb as a ligand. The purified allergen was found to be a glycoprotein with a molecular mass of 26 kDa. During the purification process the allergen was converted to more acidic proteins with the same molecular mass, suggesting that the allergen is unstable. The sugar composition and amino acid sequence of Gly m Bd 28K suggest that the allergen is a new glycoprotein with an Asn-linked sugar moiety. The distribution of the allergen in soybean products was examined by an immunoblotting technique with the mAb.