Value of eight-amino-acid matches in predicting the allergenicity status of proteins: an empirical bioinformatic investigation

The use of biotechnological techniques to introduce novel proteins into food crops (transgenic or GM crops) has motivated investigation into the properties of proteins that favor their potential to elicit allergic reactions. Allergy is an atypical detrimental immune response to proteins that are otherwise harmless, and is typically mediated by IgE antibody binding. Thus far, no single property of a protein is known to predict allergenic potential. For this reason, a weight-of-evidence approach to predicting allergenic risk has been adopted which considers multiple factors. These factors include the source of the protein, prevalence of the protein in the transgenic crop, resistance to heat and digestion, and structural similarity to known allergens [1-3].If a transgenic protein is isolated from a source organism that causes allergy, it is possible that an allergenic protein from the source organism could be inadvertently transferred to the transgenic crop. In this case, IgE antibody binding can be evaluated using serum from patients that are allergic to the source organism to determine if the transgenic protein is an allergen from that source. The intestines are considered the major site of absorbance for allergenic food proteins [4]. Increased titer of a protein in the intestines increases exposure and may favor development of food allergy. The prevalence of the transgenic protein in food and its resistance to processing and cooking may affect the amount of protein ingested, and the resistance of the protein to digestive processes, especially pepsinolysis in the stomach, will affect the amount of protein reaching the intestinal mucosa. Finally, it is possible that structural similarities between the transgenic protein and an existing allergen will be sufficient to allow IgE antibodies in patients sensitive to an existing allergen to cross-react with the transgenic protein causing allergic symptoms.The methods for evaluating several of these properties of allergens h