Characterization of 16-kDa major allergen with α-amylase inhibitor domain in tartary buckwheat seeds

Study on the reduction of Tartary buckwheat allergenicity during Pediococcus pentosaceus fermentation by HPLC-MS/MS analysis

Tartary buckwheat contains more valuable nutrients than common buckwheat, but it also contains allergenic proteins that induce allergic reactions through an IgE-mediated response. Our study demonstrated that fermentation by Pediococcus pentosaceus degrades allergenic proteins in Tartary buckwheat, as confirmed by HPLC-MS/MS analysis of polypeptides. Our results showed significant degradation of the protein after 16 h of Pediococcus pentosaceus fermentation (PP16), leading to a reduction in IgE-binding activity. Comparison with unfermented Tartary buckwheat (UTB) peptides yielded 2042 fragments, of which 756 fragments associated with allergenic proteins were upregulated. Among them, the expression of 213 fragments was reduced by 71.83%. By performing bioactivity prediction on potential allergenic peptide fragments, we identified six peptide fragments derived from Fagt 1, potentially contributing to the residual allergenicity in PP16. These suggest that Pediococcus pentosaceus fermentation can effectively destroy allergen epitopes and mitigate the allergenicity of Tartary buckwheat.

Heterologous expression and physicochemical characteristics identification of Kunitz protease inhibitor in Brassica napus

A Kunitz protease inhibitor gene (RTI; rti) was cloned from rapeseed and expressed in a Pichia pastoris expression system for the first time. After isolation and purification, the physical and chemical characteristics of the inhibitor were analyzed. The results showed that the induced expression level of the recombinant RTI reached 628 mg/L, and the specific activity of the inhibitor reached 69.6 TIU/mg protein at the shake flask fermentation level; the recombinant RTI retained more than 70% inhibitory activity between 30 and 90 °C and more than 80% inhibitory activity between pH 2.0-11.0. The metal ions Cu²⁺ and CO²⁺ and the organic reagents methanol, ethanol, acetone, and chloroform inhibit its activity. The recombinant RTI interacts with trypsin in a noncompetitive manner and has a strong and specific inhibitory effect on trypsin, a typical Kunitz trypsin inhibitor from plants. Combined with its good physical and chemical properties, recombinant RTI has the potential to be developed into an insect resistance protein.

Core epitope analysis of 16 kDa allergen from tartary buckwheat

Tartary buckwheat is widely accepted as its nutritionalvalue. Some allergic reactions hinder its utilization. This research focused on evaluating the core epitope of 16 kDa allergen (Fag t 2) in tartary buckwheat. Six B- and seven T cell epitopes of Fag t 2 were predicted, and six B cell epitope-mutants were expressed in Pichia pastoris. Bioinformatics analysis and SDS-PAGE demonstrated that the molecular weight, isoelectric point and spatial structures of six mutant allergens were similar with Fag t 2, with the same signal peptide sequences and α-amylase inhibitor domain. There was no significant change in mutants' spatial conformation confirmed by Circular Dichroism. The position K132N and peptides at 108-117 and 132-141 were the core B- and T cell epitopes of Fag t 2 confirmed by competitive inhibition ELISA and dot blot. This result was of great significance on the study of allergen epitopes in prevention and treatment of hypersensitivity.