Molecular and allergenic properties of natural hemocyanin from Chinese mitten crab (Eriocheir sinensis)

Hemocyanin in crustaceans is an allergen for humans. However, little information was available on its molecular, structural and allergenic properties. In this study, the purified natural protein was identified as Eriocheir sinensis HC by LC-MS/MS, which was allergenic because its reaction with the serum IgE of crustacean patients. Results of the molecular properties showed that, HC was resistant to trypsin digestion, but not a heat-stable protein. Boiling (55.05 & PLUSMN; 3.50 %) and steaming (66.84 & PLUSMN; 1.65 %) induced an increase in & beta;-sheet and decreased allergenicity of HC. By comparing the amino acid sequences of eight crustaceans, HC was found to be highly conserved. Five epitopes of HC were identified and validated by murine sensitization model, and two of them (P3 and P10) were exactly as the predicted by six types of bioinformatics. Multiple bioinformatics analysis combining with murine sensitization model seemed to be effective way for identification of allergenic epitopes.

Automated summary

This study discovered that hemocyanin in crustaceans is allergenic to humans, but there is limited information about its molecular, structural, and allergenic properties. The purified natural protein was identified as Eriocheir sinensis HC by LC-MS/MS, and it showed allergenicity by reacting with serum IgE from crustacean patients. Molecular property analysis revealed that HC is resistant to trypsin digestion, but not heat-stable. Boiling (55.05 ± 3.50%) and steaming (66.84 ± 1.65%) increased β-sheet content and decreased the allergenicity of HC. By comparing the amino acid sequences of eight crustaceans, HC was found to be highly conserved. Five epitopes of HC were identified and validated using a murine sensitization model, with two of them (P3 and P10) matching the predictions from six types of bioinformatics analysis. Combining multiple bioinformatics analyses with a murine sensitization model appears to be an effective method for identifying allergenic epitopes.