Effect of Covalent Interaction with Chlorogenic Acid on the Allergenic Capacity of Ovalbumin.

Ovalbumin (OVA) is a major allergen in avian egg white. Here, we investigated the conjugation of OVA and chlorogenic acid (CHA) to reduce the allergenic capacity of OVA. OVA-CHA conjugate was characterized by SDS-PAGE, MALDI-TOF-MS, differential scanning calorimetry, and multispectroscopic methods. Sites of the OVA-CHA conjugate were identified by LC-MS/MS. CHA possibly conjugated with Lys20 and Lys17 in OVA, which resulted in the unfolding of OVA. ELISA and Western blot assay indicated that the OVA-CHA conjugate reduced the IgE binding capacity of OVA. The results also indicated that the ability of the OVA-CHA conjugate to activate histamine release was reduced. The decreased allergenic capacity of OVA was attributed to changes in the protein structure. Moreover, the CHA binding site in OVA might directly shield the linear IgE epitope, thereby reducing the IgE binding ability. Also, the OVA-CHA conjugate showed high antioxidant activity. OVA conjugated with CHA may be a promising method of OVA hyposensitization.