Parvalbumins in fish and their role as food allergens: A review

Preliminary study on puffer fish proteome-species identification of puffer fish by two-dimensional electrophoresis

The aims of this work were to determine the differential characterization of the urea soluble protein components of puffer fish species and to establish a preliminary proteomic database using an immobilized pH gradient two-dimensional electrophoresis (2DE) technique. The puffer fish muscle proteins resolved into 171-260 spots in the 2DE gels, with a pI range of 3-10 and molecular mass range of 7.4-205.0 kDa, following Comassie blue staining. Puffer fish muscle proteins fell in the region with pI values of 3.5-7.0, and molecular masses of 7.4-45.0 kDa were well-resolved and were good for species comparison. The more acidic proteins of lower molecular masses showed species specific characteristics. Therefore, the species of puffer fish can be differentiated from the comparison of the characteristic 2DE protein patterns.

Purification of a 41 kDa cod-allergenic protein

Cod fish is one of the foods most frequently involved in allergy. Only the cod allergen Gad c I, a 12.3 kDa parvalbumin, has been purified and characterized. Recently, we have detected allergen bands which have not previously been described, in particular a 41 kDa protein, by Western-blot. In the present work, this protein has been purified from a crude cod extract by ammonium sulfate fractionation, hydroxyapatite chromatography and preparative electrophoresis; a single band with an Mr of 41 x 10(3) was found in silver-stained sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The amino acid composition and the isoelectric point of the protein were determined. The purified protein (p41) was shown to bind specifically to reaginic IgE from sera of cod-allergic individuals and to a monoclonal anti-parvalbumin which recognizes specifically the first calcium binding site of parvalbumins. p41 may therefore contain a calcium binding site corresponding to an IgE-epitope similar to that of Gad c I.

Isolation of parvalbumin isotypes by preparative HPLC techniques

Parvalbumins are highly stable Ca2+ binding proteins, present in large quantities in the sarcoplasmic reticulum in the white muscle of most lower vertebrates and fish. The properties of these proteins make them promising antigens for the use as a specific biomarker for fish species identification. Parvalbumin isotypes were isolated, on a preparative scale level, by use of size exclusion chromatography (SEC) and anion exchange HPLC. The utility of this technique, with regard to maximizing purified isotypes, is discussed.