Effect of 4-hydroxy-2-nonenal treatment on the IgE binding capacity and structure of shrimp (Metapenaeus ensis) tropomyosin

Abstract

Lipid peroxidation can react with free amines of proteins and induce modification of structural and functional properties. This study presents the IgE binding capacity and structural changes of shrimp tropomyosin (TM) under oxidative stress with 4-hydroxy-2-nonenal (HNE). IgE binding capacity was evaluated with the dot-blot assay and inhibition enzyme-linked immunosorbent assay. A decrease in IgE binding capacity of TM was found with 0.01mM HNE treatment, which was more significant when the HNE concentration was increased to 0.5mM. The conformational changes of TM, as characterized by fluorescence spectroscopy, circular dichroism spectroscopy and ultraviolet absorption spectroscopy, correlated well with IgE binding capacity changes. Further LC–ESI-MS/MS analyses showed that the side-chain groups of alanine, leucine, lysine and histidine had been modified by HNE. These results suggested that the HNE-induced conformational changes of TM significantly influenced its allergenicity and that these changes were caused by the modification of specific amino acids residues.