IDENTIFICATION OF THE MAJOR BROWN SHRIMP (PENAEUS-AZTECUS) ALLERGEN AS THE MUSCLE PROTEIN TROPOMYOSIN

Shrimp, a major seafood allergen, was investigated as a model food all ergen. Extracts from both shrimp (Penaeus aztecus) meat and cooking fl uid contain a substantial and similar amount of allergenic activity. A 36-kD allergen, demonstrated in both extracts by SDS-PAGE/Westem blot analysis, reacted with 28/34 (82%) sera from shrimp-sensitive, skin t est and RAST-positive, individuals. This allergen, named Pen a I, was isolated by SDS-PAGE; its amino acid composition was rich in aspartic and glutamic acids. A 21-residue peptide, obtained from endoproteinase Lys-C digested Pen a I by high-performance liquid chromatography, dem onstrated significant homology (60-87%) with the muscle protein tropom yosin from various species and origins. The greatest homology (87%) wa s noted with tropomyosin of the fruit fly (Drosophila melanogaster) re flecting the phylogenic relationship between these two arthropods. The se studies demonstrate that tropomyosin is the major shrimp allergen. Although the amino acid sequence of this shrimp muscle protein shares considerable homology with tropomyosins of other species including man , significant differences remain in allergenic activity.