title: Effect of pH shifts on IgE-binding capacity and conformational structure of tropomyosin from short-neck clam (Ruditapes philippinarum).
abstract: The aim of the present study was to assess pH-induced changes in conformational structures and potential allergenicity of tropomyosin from short-neck clams. As defined with circular dichroism (CD), an unfolded structure was found at pH values ranging from 2.0 to 5.0, followed by the loss of secondary structure at pH of 1.0. Correspondingly, surface hydrophobicity was reduced by 97.7% when pH was reduced from 7.0 to 1.0. Further indirect ELISA and dot-blot results of pH shifted tropomyosin showed that potential allergenicity correlated well with structural changes, as well as with SGF digestibility. Allergenicity decreased significantly with unfolding of the protein and was stable when surface hydrophobicity recovered back to neutral conditions. These results showed that conformational changes in tropomyosin induced by pH shifting significantly influenced the allergenicity of tropomyosin, and that the resulting changes occurred predominately in the acidic pH range.
authors.affiliation: Lab of Food Safety, College of Food Science and Engineering, Ocean University of China, Qingdao 266003, Shandong, China.
authors.forename: Haixin
authors.initials: H
authors.lastname: Lin
authors.affiliation: Lab of Food Safety, College of Food Science and Engineering, Ocean University of China, Qingdao 266003, Shandong, China. Electronic address: lizhenxing@ouc.edu.cn.
authors.forename: Zhenxing
authors.initials: Z
authors.lastname: Li
authors.affiliation: Lab of Food Safety, College of Food Science and Engineering, Ocean University of China, Qingdao 266003, Shandong, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Lin
authors.affiliation: Lab of Food Safety, College of Food Science and Engineering, Ocean University of China, Qingdao 266003, Shandong, China.
authors.forename: Yongna
authors.initials: Y
authors.lastname: Song
authors.affiliation: Lab of Food Safety, College of Food Science and Engineering, Ocean University of China, Qingdao 266003, Shandong, China.
authors.forename: Liangtao
authors.initials: L
authors.lastname: Lv
authors.affiliation: Lab of Food Safety, College of Food Science and Engineering, Ocean University of China, Qingdao 266003, Shandong, China.
authors.forename: Zina
authors.initials: Z
authors.lastname: Hao
mesh_terms: D000485:Allergens / Q000737:chemistry / Q000276:immunology; D000818:Animals; D049872:Bivalvia / Q000276:immunology*; D002942:Circular Dichroism; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D007073:Immunoglobulin E / Q000737:chemistry*; D007074:Immunoglobulin G / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D012758:Shellfish / Q000032:analysis; D014335:Tropomyosin / Q000737:chemistry* / Q000276:immunology
chemical_list: D000485:Allergens; D007074:Immunoglobulin G; D014335:Tropomyosin; D007073:Immunoglobulin E
keywords: 1-Anilino-8-naphthalene-sulfonate (PubChem CID: 1369); 3,3′,5,5′-Tetramethylbenzidine (PubChem CID: 41206); Acrylamide (PubChem CID: 6579); Allergen; Brilliant Blue R (PubChem CID: 61365); IgE-binding; Short-neck clam; Tropomyosin; Tween 20 (PubChem CID: 443314); pH shift