Submitted to: Journal of Allergy Clinical Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/13/1999
Publication Date: 2/20/2000
Interpretive Summary: Food allergies are caused because some people react adversely to certain proteins in the food source. Peanuts and soybeans seem to have such proteins. There are specific regions of the proteins that cause more reactions than others. Proteins are composed of a series of amino acids attached to one another. This study has found that if one amino acid is substituted for another in the regions of the protein that are most reactive, the allergenicity of the protein may be reduced. This might be important in future breeding, processing of molecular engineering of these foods to change the allergy-producing proteins to non-allergy proteins.
Technical Abstract: Background: Peanuts and soybeans are 2 foods that have been shown to be responsible for many atopic disorders. Because of their nutritional benefit, soybean proteins are now being used increasingly in a number of food products. Previous studies have documented multiple allergens in soybean extracts, including glycinin, beta-conglycinin, and the P34/Gly m Bd 30K protein. Objective: Our overall goal was to identify soybean-specific allergens to begin to understand molecular and immunochemical characteristics of legume proteins. The specific aim of the current investigation was to identify the essential amino acid residues necessary for IgE binding in the 5 distinct immunodominant epitopes of P34/Gly m Bd 30K. Methods: Serum IgE from 6 clinically sensitive soybean-allergic individuals was used to identify P34/Gly m Bd 30K in the native and single amino acid substituted peptides with use of the SPOTS peptide synthesis technique to determine critical amino acids required for IgE binding. Results: The intensity of IgE binding and epitope recognition by serum IgE from the individuals varied substantially. With the serum from 6 clinically soybean-sensitive individuals, 2 of the 5 immunodominant epitopes could be mutagenized to non-IgE binding peptides. Conclusions: Single-site amino acid substitution of the 5 immunodominant epitopes of Gly m Bd 30K with alanine revealed that IgE binding could be reduced or eliminated in epitopes 6 and 16 in the serum obtained from 6 soybean-sensitive patients.