Structural Database of Allergenic Proteins (SDAP)

The Structural Database of Allergenic Proteins (SDAP) brings together data from diverse sources on over 800 allergen sequences and their epitopes in a cross-referenced format. Special methods developed for SDAP, such as the property distance (PD) scale, automatically detect peptides in the ensemble of allergen sequences that have physicochemical properties similar to known immunoglobulin E (IgE) epitopes. Comparing the structure of food allergens with allergenic proteins from exposure to pollens, insect dust, or other aeroallergens can give valuable information about the sensitization process. Any novel protein introduced into a food crop should have a low potential to be an allergen. This chapter deals with database approaches to determine the allergenic potential of a test protein, based on similarity to known allergens. It outlines basic methodology to identify cross-reacting proteins in food sources and predict the potential allergenicity of novel proteins. The chapter concentrates on the SDAP, which has been specifically designed to allow combined analysis of the sequence, structure, and epitopes of allergens. It also shows how SDAP and the methods for sequence and peptide comparison incorporated therein can be used to predict cross-reactive allergens in foods and determine common properties of their IgE epitopes. The second half of the chapter demonstrates how SDAP has allowed one to rapidly collect data pertinent to very basic questions about allergens, such as whether enzymatic activity is related to allergenicity. The chapter provides an overview of the information and methods incorporated into the cross-referenced (MySQL-Linux) lists of data.