RESUMO
A lipid transfer protein (LTP, Cor a 8) together with the 11S (Cor a 9) and 7S seed storage globulins (Cor a 11) are major food allergens present in hazelnut. Methods are described for their purification and characterisation using in-gel tryptic digestion mass spectrometry to confirm their identities and circular dichroism and Fourier-transform infrared spectroscopies to demonstrate that they are authentically folded. Preliminary immunochemical studies have also confirmed that the purified preparations retain their immunological properties in terms of immunoglobulin E binding, determined by immunoblotting using serum from hazelnut allergic patients. These preparations form a basis for development of improved methods of diagnosis of food allergy based on the concept of component-resolved diagnosis.
Assuntos
Alérgenos/isolamento & purificação , Corylus/imunologia , Hipersensibilidade a Noz/etiologia , Proteínas de Plantas/isolamento & purificação , Sementes/imunologia , Alérgenos/química , Alérgenos/imunologia , Sequência de Aminoácidos , Cromatografia em Gel , Cromatografia Líquida de Alta Pressão , Dicroísmo Circular , Humanos , Immunoblotting , Imunoglobulina E/metabolismo , Dados de Sequência Molecular , Proteínas de Plantas/química , Proteínas de Plantas/imunologia , Estrutura Secundária de Proteína , Sementes/química , Espectrometria de Massas por Ionização por Electrospray , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
Peanut is a major cause of type 1 hypersensitive reactions including anaphylaxis. This results from the presence of a number of protein allergens, six of which are being studied as part of the EU FP6 EuroPrevall programme. These are Ara h 1 (7S globulin), Ara h 2, Ara h 6 (2S albumins), Ara h 3/4 (11S globulins) and Ara h 8 (Bet v 1 homologue). Methods for the purification of Ara h 1, Ara h 3/4, Ara h 2 and Ara h 6 from peanut seeds and for the production of recombinant Ara h 8 in Escherichia coli are described with spectroscopic analyses being used to confirm that they are authentically folded. N-terminal sequencing of the proteins purified from peanut seeds also revealed details of the differences between isoforms and their generation by proteolytic processing within the seed. Preliminary IgE binding studies of the purified allergens confirmed that they retained their immunological properties indicating their suitability for use in allergy diagnosis.
Assuntos
Alérgenos/isolamento & purificação , Arachis/imunologia , Hipersensibilidade a Amendoim/diagnóstico , Alérgenos/química , Alérgenos/imunologia , Sequência de Aminoácidos , Sequência de Bases , Humanos , Imunoglobulina E/imunologia , Dados de Sequência Molecular , Estrutura Secundária de ProteínaRESUMO
Apple (Malus domestica) is the most widely cultivated fruit crop in Europe and frequently causes allergic reactions with a variable degree of severity. So far, four apple allergens Mal d 1, Mal d 2, Mal d 3 and Mal d 4 have been identified. Mal d 1, a Bet v 1 related allergen, and Mal d 4, apple profilin, are sensitive to proteolytic degradation, whereas Mal d 2, a thaumatin-like protein and Mal d 3, a nonspecific lipid transfer protein, are rather stable to proteolytic processes. Mal d 1 and Mal d 4 were purified after expression in Escherichia coli expression system, while Mal d 2 and Mal d 3 were purified from apple fruit tissue. All purified proteins were subjected to detailed physicochemical characterisation to confirm their structural integrity and maintained IgE binding capacity. Detailed investigations of carbohydrate moieties of Mal d 2 demonstrated their involvement in the overall IgE binding capacity of this allergen. It was concluded that the folded structure and IgE binding capacity of all four allergens were preserved during purification.
