Methods: Peanut extracts were treated overnight with and without 10 mM p- aminobenzamidine (pABA, a protease inhibitor) in the presence of 1% glutaraldehyde, pH 8.5. Various amino acids (e.g., glycine, lysine, phenylalanine, and histidine) with functional groups similar to pABA were also used for the treatment. After treatment, samples were centrifuged and concentrated using centrifugal filters. SDS-PAGE and IgE binding in Western blots were performed.
Results: SDS-PAGE showed that Ara h 1 and other proteins but not Ara h 2 and Ara h 6 were removed from the extract after treatment with pABA. Data on IgE binding indicated an absence of Ara h 1 in the treated extract. By contrast, residual Ara h 1 and other soluble protein polymers besides Ara h 2/Ara h 6 were seen in the extracts treated without pABA but with glutaraldehyde. The soluble protein polymers were recognized by IgE antibodies. Treatment with various amino acids provided the same results.
Conclusions: Treatment with pABA in the presence of glutaraldehyde resulted in a peanut extract that contained no Ara h 1 but did contain Ara h 2/Ara h 6. Total IgE binding was reduced as a result. The pABA method thus appears to have a potential for the production of hypoallergenic peanut extracts.