Biology Reference
In-Depth Information
Chapter 50
Immunoproteomics Analysis of Food Allergens
Rika Nakamura and Reiko Teshima
Abstract
Immunoblot-coupled proteomics based on two-dimensional polyacrylamide gel electrophoresis
(2D-PAGE), namely, immunoproteomics, has been used for comprehensive identifi cation of food aller-
gens, because it is a simple and inexpensive tool for rapid identifi cation of several IgE-binding proteins. In
this section, we describe our protocols for identifi cation of food allergens using immunoproteomics and
discuss a few technical points in detail.
Key words
Food allergy, Allergen, IgE, Immunoproteomics, Identifi cation, 2D-PAGE, MS/MS
1
Introduction
Some plants may trigger hypersensitivity reactions when patients
with allergic diathesis eat parts of these plants or inhale their pol-
len. Most allergens in plants are proteinases, seed storage proteins,
or enzyme (e. g., trypsin/amylase) inhibitor proteins. For identifi -
cation of novel allergens, those allergens should have been extracted
from food, purifi ed and isolated by chromatography, such as ion-
exchange and gel fi ltration, and their amino acid sequences decoded
[
1
-
3
]. These methods involve complex steps, such as purifying the
allergens from the crude extracts, and confi rmation, at every step,
by enzyme-linked immunosorbent assay (ELISA) or immunoblot
analysis with the sera of the patients with food allergies, that the
protein fraction has the capacity to bind IgE. Moreover, conven-
tional methods to identify multiple allergens in foods are time-
consuming, because only one allergen can be identifi ed in a series
of experiments. Proteomics has, therefore, been used for compre-
hensive identifi cation of food allergens [
4
].
Immunoproteomics is a method coupling immunohistochemi-
cal analysis and proteomics based on 2-dimensional polyacrylamide
gel electrophoresis (2D-PAGE). For identifi cation of allergens,
immunoglobulin E (IgE)-binding protein spots are detected on a
2D map of the food extract, the spots are excised from the 2D gel,
