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BACKGROUND Molluscan shellfish, including oysters, often cause allergic reactions in sensitive people throughout the world. It has been demonstrated that arginine kinase (AK) is one of the major allergens of oyster. The present study aimed to evaluate the immunoreactivity and structure of oyster AK as affected by heat treatment, pH change, and in vitro digestion. What is more, the immunoglobulin E‐binding epitopes of this allergen were also predicted and validated. RESULTS Thermal and pH assays revealed that AK was unstable at temperature >40 °C or pH ≤5.0 by sodium dodecyl sulfate polyacrylamide gel electrophoresis and circular dichroism, and the digestibility assays suggested that AK was more easily digested by pepsin than by trypsin and chymotrypsin. The potential epitopes were predicted through immunoinformatics tools, and seven linear epitopes were identified by indirect competition enzyme‐linked immunosorbent assay with pooled sera and individual serum from oyster‐allergic patients. The critical amino acids in each epitope were also confirmed using mutant peptides. These linear epitopes and critical amino acids were apt to distribute on the outer surface of homology‐based AK model. Moreover, the three denaturants (sodium dodecyl sulfate, β‐mercaptoethanol, and urea) can destroy the spatial structure of AK and increase or reduce its allergenicity by denaturation treatments. CONCLUSION Processing conditions lay the foundation for the variation of allergenicity. Seven linear epitopes and their critical amino acids were identified by indirect competitive enzyme‐linked immunosorbent assay. These findings will be helpful in allergy diagnosis and development of hypoallergenic products in the near future. © 2021 Society of Chemical Industry.

BACKGROUND: Food allergy is a serious public nutritional health problem that has attracted extensive worldwide attention. Shellfish allergy is a long-lasting disorder that has a lifelong impact on health. Sarcoplasmic calcium-binding protein (SCP) plays a vital role in cell and muscle functions and has been identified as an allergen in oyster.RESULTS: In this study, recombinant SCP (rSCP) with a molecular mass of 21 kDa was produced and identified based on SCP amino acid sequencing of Pacific oyster (Crassostrea gigas), and was used as a follow-up experimental material. Its physicochemical characterization showed that purified rSCP is highly stable to heat and acid-alkali and trypsin digestion but less resistant to pepsin digestion. We established an animal sensitization model and rSCP displayed stronger Immunoglobulin E (IgE)-binding activity with rat serum in the rSCP + cholera toxin (CT) group compared with the CT group and a control group. Five epitope peptides were identified as linear immunodominant epitopes by indirect competitive enzyme-linked immunosorbent assay (icELISA) for the first time. We also found that conformational epitopes may play a major role in the immunoreactivity of SCP.CONCLUSION: These results are significant for understanding hypersensitization of humans to oyster and offer available preventive measures and treatment programs in further research.

In this study, the effect of corn oligopeptides (COPs) with liver protection activity on mice with hepatic fibrosis (HF) induced by carbon tetrachloride (CCl4) was studied. It was proved that COPs can ameliorate the liver injury and inflammation caused by CCl4 by histopathology and enzyme‐linked immunosorbent assay in mice. The expression of Akt/NF‐κB inflammatory pathway was determined by real‐time polymerase chain reaction (RT‐PCR) and western blotting (WB). The results showed that COPs inhibited the expression of key proteins in the inflammatory pathway. In conclusion, the results of this study suggested that COPs could improve CCl4‐induced HF by improving liver injury, reducing the expression of inflammatory factors, and inhibiting the expression of inflammatory signaling pathways. Practical applications The corns around the world are mainly used as animal feed, and the liver protective activity of corn oligopeptides (COPs) is rarely applied to the market. The development of COPs liver protective food can prevent the occurrence of liver‐related diseases such as hepatic fibrosis to a certain extent. Developing COPs liver protecting food can improve the utilization value of corn. It is hoped that this study can provide experimental support for the application of COPs in liver protection food.