ISOLATION AND CHARACTERIZATION OF A MAJOR ALLERGEN IN KIWI FRUIT

The isolation of an important allergen in kiwi fruit (Actinidia chinen sis) by ion-exchange chromatography (IEC) and micropreparative SDS-PAG E followed by electroelution is reported. The purity of the allergen w as analysed by SDS-PAGE and immunoblotting with sera from patients who have an allergy to kiwi. The allergen was shown to have a molecular w eight of 43 kDa by SDS-PAGE/immunoblotting and an isoelectric point of approximately 6.9 as estimated by IEC. In accordance with World Healt h Organization nomenclature, this allergen is called Act c 2. By immun oblot inhibition it was shown that epitopes from different allergens i n kiwi fruit are also located on Act c 2. N-terminal amino acid sequen cing of 17 amino acid residues did not reveal homology with the major allergens in birch pollen (Bet v 1), apple (Mal d 1) or with other pro teins of allergenic plant foods, In addition, the isoelectric point of a 67-kDa allergen in kiwi fruit was estimated to be 7.4 by IEC, but m icropreparative isolation of this allergen failed because of its very low content in the fruit.