Emerging food allergens: Identification of polyphenol oxidase as animportant allergen in eggplant (Solanum melongena L.).

Harish Babu, B. N. and Wilfred, A. and Venkatesh, Y. P. (2017) Emerging food allergens: Identification of polyphenol oxidase as animportant allergen in eggplant (Solanum melongena L.). Immunobiology, 222 (2). pp. 155-163. ISSN 0171-2985

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Abstract

tAlthough many allergens have been detected in eggplant (Solanum melongena L.), their identity have notbeen elucidated. The aim of this study was to investigate whether polyphenol oxidase (PPO), an importanteggplant enzyme, acts as an allergen. The proteins of eggplant peel extract were separated on phenyl-Sepharose (PS), and analyzed by skin prick test (SPT), ELISA and IgE-immunoblotting; the componentswere analyzed for PPO activity, presence of protein–bound copper, and recognition by rabbit polyclonalanti-sweet potato PPO antiserum. LC–MS/MS and in silico analysis were employed to identify the sep-arated allergens and prediction of IgE epitopes. Eggplant allergens were separated into 5 components(PS1–PS5), of which component PS2 exhibited high specific PPO activity. SPT and ELISA with PPO-richpool (PS2) were positive in all 6 eggplant-allergic subjects; the 43, 64 and 71 kDa proteins displayedstrong IgE-binding ability. The 64 and 71 kDa IgE-binding proteins show PPO activity, presence of cop-per, and recognition by anti-sweet potato PPO antiserum, clearly identifying them as PPOs; the 43 kDaprotein appears to be a degradation product of the 64 or 71 kDa proteins based on enzymic activity andrecognition by PPO antiserum. The 64 kDa protein upon further resolution by SDS-PAGE displayed twocomponents (identified as eggplant PPO1 and PPO4 by LC–MS/MS). Based on bioinformatics approaches,PPO4 has been identified as an allergen since it harbors an IgE epitope. This study clearly demonstratesthat the 64 and 71 kDa allergens in eggplant peel are PPOs based on enzymic activity and recognition byPPO antiserum; the 64 kDa copper-containing protein is identified as one of the several eggplant allergens(Sola m PPO4). This is the first instance of polyphenol oxidase being identified as a new food allergen.

Item Type:	Article
Uncontrolled Keywords:	Bioinformatics Eggplant Food allergen IgE epitope predictionin silico analysis Polyphenol oxidase Protein-bound copper
Subjects:	600 Technology > 01 Medical sciences > 01 Allergy 600 Technology > 08 Food technology > 23 Vegetables
Divisions:	Dept. of Biochemistry
Depositing User:	Food Sci. & Technol. Information Services
Date Deposited:	01 Feb 2018 11:05
Last Modified:	01 Feb 2018 11:05
URI:	http://ir.cftri.res.in/id/eprint/13394

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