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 a nd characterized. Recently, we have detected allergen bands which have not previously been described, in particular a 41 kDa protein, by Wes tern-blot. In the present work, this protein has been purified from a crude cod extract by ammonium sulfate fractionation, hydroxyapatite ch romatography and preparative electrophoresis; a single band with an M- r of 41x10(3) was found in silver-stained sodium dodecyl sulfate-polya crylamide gel electrophoresis. The amino acid composition and the isoe lectric point of the protein were determined. The purified protein (p4 1) was shown to bind specifically to reaginic IgE from sera of cod-all ergic individuals and to a monoclonal anti-parvalbumin which recognize s specifically the first calcium binding site of parvalbumins. p41 may therefore contain a calcium binding site corresponding to an IgE-epit ope similar to that of Gad c I. (C) 1998 Elsevier Science B.V.