Team:Linkoping Sweden/Project/Culprit

The picture represents a ribbon diagram of Ara h1 tertiary structure. The numbered red areas are IgE binding epitopes 10–22.

Peanut allergy appears early in life and tends to persist indefinitely compared to other foodallergies. Symptoms ranging from urticaria to severe, systemic anaphylaxis.

Different proteins are associated with these clinical reactions. The ara h1 protein is an important allergen and is recognized by 90 % of peanut-sensitive persons¹. It is 418 aminoacids in length and belongs to the vicilin family of seed storage proteins. The structure consists of two sets of opposing antiparallel β-sheets with terminal regions of α-helical bundles. Ara h1 is stable to digestion and survives intact in many food processing methods. It contains protease digestion sites which are inaccessible due to the compact tertiary structure.

The body thinks that the protein is an immunological threat and generates IgE, immunoglobulin E. IgE binds to ara h1 protein and activate mastcells to release histamines, causing an allergic reaction. The mastcell receptors cross-link, inducing a signal transduction that result in degranulation. Ara h1 protein consists of 23 IgE-binding epitopes, varying from 6-8 aminoacids in length. There is no common aminoacid sequence between the epitopes. The most critical part of the sequence is the hydrophobic residues. It has been shown that substitution of a single aminoacid leads to loss of IgE-bindning¹.

Mastcell (Click to enlarge).