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

This work reports on the effect of heat treatment on the protein conformational stability of intact and post-translationally cleaved peanut allergen Ara h 6 in relation to IgE-binding. Intact and post-translationally cleaved Ara h 6 are structurally similar and their strong resistance to denaturant-induced unfolding is comparable. Only upon exposure to autoclave conditions the two forms of Ara h 6 demonstrated susceptibility to irreversible denaturation resulting in a significant decrease in IgE-binding potency. This reduction is for the intact protein more pronounced than for than for the cleaved form. This is attributed to less conformational constrains of the cleaved form compared to intact, as suggested by the 2-fold lower activation energy for unfolding found for the cleaved form. Overall, harsh conditions are required to denature Ara h 6 and to significantly reduce its IgE-binding potency. The cleaved form possesses more resistance to such denaturation than the intact form.