Effect of heat treatment on the conformational stability of intact and cleaved forms ofthe peanut allergen Ara h 6 in relation to its IgE-binding potency

Abstract

This work reports on theeffect of heat treatment on the protein conformational stabilityof intact and post-translationallycleaved peanut allergen Ara h 6 in relation to IgE-binding. Intact and post-translationallycleaved Ara h 6 are structurally similar and theirstrong resistance to denaturant-inducedunfolding is comparable. Only upon exposure toautoclave conditions the twoforms of Ara h 6 demonstrated susceptibility toirreversible denaturationresulting in a significant decrease in IgE-binding potency. Thisreduction isfor the intact protein more pronounced than for than for the cleaved form. This isattributed to less conformational constrains of the cleaved form comparedtointact, as suggested by the 2-fold lower activation energy for unfoldingfound for the cleavedform. Overall, harsh conditionsare required to denature Ara h 6 and to significantly reduce its IgE-bindingpotency. The cleavedform possesses more resistance to such denaturation than the intactform.

Keywords: Allergen; Circular dichroism; Conformation; Heat; IgE-binding; Peanut; Stability.