Exploration of Non‐Covalent Interactions of Peanut Allergen Ara h 2 With Tannic Acid: Insights Into Molecular Structure and In Vitro Allergenicity

The molecular structure and surface properties of peanut proteins are altered by their non-covalent interactions with food polyphenols, which alter their allergenicity. In our research, the interactions between the critical peanut allergen (Ara h 2) and a model polyphenol (tannic acid [TA]) were studied utilizing experimental (spectroscopy and calorimetry) and molecular docking methods. Ultraviolet (UV) and circular dichroism (CD) spectroscopy analysis indicated that the microenvironment polarity and secondary/tertiary structure of Ara h 2 were changed due to its interaction with TA. Specifically, degree of molecular disorder increased, and the surface hydrophobicity of the polypeptide decreased after Ara h 2 interacted with TA. Analysis using fluorescence quenching, isothermal titration calorimetry, and molecular docking showed that the main non-covalent interactions were hydrogen bond formation between the Ara h 2 and TA. Binding site analysis using molecular docking indicated that the TA may have interacted with specific amino acids in the polypeptide chain, including Lys 31, Arg 34, Asp 35, Trp 44, Ser 54, Arg 59, Arg 60, Arg 122, Glu 123, and Gln 130. These amino acids are known to be part of the IgE epitope regions of Ara h 2, and so TA binding might be expected to impact peanut protein allergenicity. Indeed, an enzyme-linked immunosorbent assay (ELISA) study indicated that the IgE binding capacity of Ara h 2 was reduced after interacting with TA in a dose-dependent manner. This study enriches the understanding of the interactions between peanut protein allergens and small-molecule nutrients and provides a method for reducing the potential allergenicity of Ara h 2. PRACTICAL APPLICATIONS: Employing the plant polyphenols as a means to modulate the activity of food allergens could potentially offer a breakthrough in managing food allergies. The strategic non-covalent binding of polyphenols, exemplified by TA, to the peanut allergen Ara h 2, may effectively lower its capacity to trigger allergic reactions, thereby offering an approach to mitigating peanut sensitization risks. The study examined the alterations in the structure and allergenic properties of Ara h 2 following its interaction with TA. This investigation was poised to accelerate the identification of TA's potential to inhibit peanut-induced allergic responses through allergen binding.