Identification of tropomyosin and arginine kinase as major allergens of Portunus pelagicus (blue swimming crab).
ABSTRACT Crab is an important source of food allergen. Tropomyosin represents the main crab allergen and is responsible for IgE cross-reactivity between various species of crustaceans. Recently, other new crab allergens including arginine kinase have been identified. However, information on allergens of the local Portunidcrab is not available. Thus, the aim of this study was to identify the major allergens of Portunus pelagicus (blue swimming crab) using the allergenomics approach. Raw and cooked extracts of the crab were prepared from the crab meat. Protein profile and IgE binding pattern were demonstrated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting using sera from 30 patients with crab allergy. The major allergens of the crab were then identified by two-dimensional electrophoresis (2-DE), followed by mass spectrometry analysis of the peptide digests. The SDS-PAGE of raw extract revealed approximately 20 protein fractions over a wide molecular weight range, while cooked extract demonstrated fewer protein bands. The raw extract also demonstrated a higher number of IgE reactive bands than the cooked extract. A heat-resistant protein of 36 kDa has been identified as the major allergen in both raw and cooked extracts. In addition, a heat-sensitive protein of 41 kDa was also recognized as a major allergen in raw crab. The 2-DE gel profile of the raw extract demonstrated about >100 distinct proteins spots and immunoblotting of the 2-DE profile demonstrated at least 12 different major IgE reactive spots with molecular masses between 13 to 250 kDa and isoelectric point (pI) values ranging from 4.0 to 7.0. The 36 and 41 kDa proteins were identified as the crab tropomyosin and arginine kinase, respectively by mass spectrometry. Therefore, this study confirmed that tropomyosin and arginine kinase are the major allergens of the local Portunid crab, P. pelagicus.
Article: Entomophagie et risque allergique[Show abstract] [Hide abstract]
ABSTRACT: Though traditionally confined to some Asian, African and South American countries, consumption of edible insects, known as entomophagy, is gradually spreading to the USA and European countries. Although it remains rather limited, essentially for psychological reasons, in some European countries entomophagy is developing with the emergence of companies dedicated to the mass production of edible insects, together with the opening of restaurants specialized in menus featuring such insects. In spite of the nutritional interest and apparent safety of eating edible insects, it is advisable that we be aware of the allergic risk, which this may represent for people allergic to shellfish, mollusks or house dust mites. Various panallergens such as tropomyosin and arginine kinase, which are common to insects, crustaceans, mollusks, dust mites and nematodes, can be responsible for the cross-reactivity between these organisms of different origins. In addition to these panallergens, other allergens more specifically associated with insects could likewise trigger allergic reactions. However, these allergens are still not well known and remain to be identified and characterized. In the meantime and because of the existence of cross-reactive allergens in insects, it seems wise to advise individuals known to be allergic to shellfish or mollusks to avoid eating edible insects.Revue Française d'Allergologie 06/2014; · 0.35 Impact Factor
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ABSTRACT: Arginine kinase (AK) has attracted considerable attention because it has been identified as a shellfish allergen. However, little information is available about AK in crayfish (Procambarus clarkii). In this study, crayfish AK was purified and cloned. Its physicochemical properties, processing stability, and immunological characteristics were analyzed. Crayfish AK was purified by column chromatography, which revealed a single band with molecular mass of 40 kDa; this result was further confirmed by mass spectrometry. The full-length gene sequence of crayfish AK was 1,462 bp and encoded a protein of 357 amino acid residues. The results of this study revealed that crayfish AK is a glycoprotein with an isoelectric point of approximately 6.5. Thermal stability assays revealed that crayfish AK easily forms aggregates at temperatures >44°C and was stable at pH 4.0-8.0. SDS-PAGE and dot blotting were used to assess processing stability of purified AK. The results revealed that the IgE-binding activity of crayfish AK is reduced after boiling.Food and chemical toxicology: an international journal published for the British Industrial Biological Research Association 09/2013; · 2.99 Impact Factor
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ABSTRACT: Shellfish allergy is of increasing concern, as its prevalence has risen in recent years. Many advances have been made in allergen characterization. B cell epitopes in the major allergen tropomyosin have been characterized. In addition to tropomyosin, arginine kinase, sarcoplasmic calcium-binding protein, and myosin light chain have recently been reported in shellfish. All are proteins that play a role in muscular contraction. Additional allergens such as hemocyanin have also been described. The effect of processing methods on these allergens has been studied, revealing thermal stability and resistance to peptic digestion in some cases. Modifications after Maillard reactions have also been addressed, although in some cases with conflicting results. In recent years, new hypoallergenic molecules have been developed, which constitute a new therapeutic approach to allergic disorders. A recombinant hypoallergenic tropomyosin has been developed, which opens a new avenue in the treatment of shellfish allergy. Cross-reactivity with species that are not closely related is common in shellfish-allergic patients, as many of shellfish allergens are widely distributed panallergens in invertebrates. Cross-reactivity with house dust mites is well known, but other species can also be involved in this phenomenon.Clinical Reviews in Allergy & Immunology 05/2014; · 4.73 Impact Factor