Two-dimensional electrophoresis and IgE-mediated food allergy

Food allergy is recognized as one of the major health concerns. It is estimated that ca. 4% of the population is affected by food allergenic disorders. Food allergies are defined as IgE-mediated hypersensitivity reactions. Foods such as peanuts, tree nuts, wheat, soy, cow's milk, egg, fish and shellfish are regarded as responsible for the majority of reactions. The ubiquitous presence of allergens in the human foods coupled with an increased awareness of food allergies warrants to undertake appropriate preventive measures for protecting sensitive consumers from unwanted exposure to offending food allergens. 2-DE followed by immunoblotting and identification of IgE-reactive proteins, as a proteomic approach to identify new allergens in foods, are reviewed. Specific examples of identification of allergens in foods and beverages by using 2-DE and IgE are described. Protein profiling using 2-DE and allergens detection by IgE has become a powerful method for analyzing changes of allergens content in complex matrix during food processing.

Phthalocyanine-dyed fibers adsorb allergenic proteins

Phthalocyanine (Pc)-dyed fiber is reported to reduce atopic symptoms in some patients when they use underwear made of the fiber. We investigated the adsorption of allergens on Pc-fiber. Pc-fiber trapped house dust/pollen/food allergens with varied molecular weight and pI. The adsorbed allergens were released in the presence of mild detergent. Pc-fiber did not change the molecular weight or disulfide bonding of the allergens. These observations imply that Pc-fiber is applicable as an "allergen trap" for a wide variety of products.

Disulfide proteome yields a detailed understanding of redox regulations: A model study of thioredoxin-linked reactions in seed germination

Accumulating evidence suggests that redox regulations play important roles in a broad spectrum of biological processes. Recently, Yano et al. developed a disulfide proteome technique that comprehensively visualizes redox change in proteins. In this paper, using the disulfide proteome, we examined rice bran and identified fragments of embryo-specific protein and dienelactone hydrolase as putative targets of thioredoxin. Also, monitoring of the endogenous and recombinant effects of thioredoxin on rice bran proteins and supporting in vivo observations propose a mechanism of redox regulation in seed germination, in which thioredoxin activates cysteine protease with a concurrent unfolding of its substrate, the embryo-specific protein. Our findings suggest that thioredoxin controls the lifetime of specific proteins effectively by regulating the redox reactions coordinately. The model study demonstrates that the disulfide proteome technique is useful not only for identifying targets of thioredoxin, but also for clarify the detailed mechanism of redox regulation.

Fluorescent labeling of disulfide proteins on 2D gel for screening allergens: a preliminary study

An experimental protocol was established to detect disulfide proteins as fluorescent spots on 2D gel. In summary, free sulfhydryl groups in a protein mixture were capped with nonfluorescent iodoacetamide, followed by chemical reduction of disulfide bonds, and labeling of newly exposed sulfhydryl groups with the fluorescent probe, monobromobimane. Disulfide proteins were detectable as fluorescent spots under the UV lamp. As accumulating evidence suggests that disulfide bonds are responsible for the allergenicity of many proteins, we sought to use this protocol to find new allergens. In a model experiment using soybean trypsin inhibitor, a well-known allergen with disulfide bonds, and myoglobin, which has a free sulfhydryl group, only the former was labeled with fluorescence. Application of the protocol to mite and pollen extracts facilitated detection of known allergens or putative allergens exhibiting sequence similarities to known allergens. In this note, we report the protocol as a complementary tool for screening allergens, which is now solely dependent on immunological recognition.