Cross-linking of peanut allergens by polyphenol oxidase and its effect on peanut allergenicity☆

Abstract 

Rationale

Polyphenol oxidase (PPO) catalyzes the cross-linking of proteins. The objective was to determine if PPO induces cross-linking of peanut allergens and reduces peanut allergenicity.

Methods

Protein extracts were prepared from defatted roasted peanut meals. The extracts were then incubated with PPO at 37 C, pH 7, for 60 min, and analyzed by SDS-PAGE, blots and competitive ELISA, using a pooled serum from peanut allergic individuals.

Results

PPO reacted with two peanut proteins only. These were the major allergens Ara h 1 and Ara h 2. After PPO treatment, Ara h 1 and Ara h 2 were each seen to decrease significantly in levels. High molecular-weight polymers were formed due to the cross-linking of the allergens induced by PPO. IgE binding of the POD-treated peanut extracts was reduced approximately 4-fold as compared to the untreated.

Conclusions

A significant decrease in the levels of two major peanut allergens Ara h 1 and Ara h 2 was observed after PPO treatment. Cross-linking of the allergens contributed to this decrease. A 4-fold reduction in IgE binding was observed. This suggests that PPO is capable of inducing a small reduction in peanut allergenicity.

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