N-terminal sequences of high molecular weight allergens from celery tuber

Background Celery tuber is an important source of food allergens. Low molec ular weight celery allergens were identified as homologues of Bet v 1 and p rofilin. Little is known about the relevant allergens with molecular weight s between 45 and 60 kDa, which cross-react with other plant food and pollen allergens. Objective The aim of this study was to isolate cross-reactive, high molecul ar weight allergens from celery and to characterize them by N-terminal sequ encing. Methods High molecular weight allergens of celery were identified by immuno globulin (Ig) E immunoblotting with patients' sera, and the IgE-binding pat terns were compared with those of the monoclonal antibirch pollen antibody BIP3, as well as of a polyclonal rabbit anti-Art v 1 antiserum. Two indepen dent methods, elution from preparative SDS-PAGE or anion exchange chromatog raphy, were used to purify the IgE-binding celery proteins of interest. The isolated proteins were examined by N-terminal sequencing and IgE-immunoblo ts. Results Celery allergens with molecular masses of 55, 58 and 63 kDa, which were also recognized by the monoclonal BIP3 antibody and a polyclonal anti- Art v 1 antiserum, were isolated. The 63-kDa allergen was N-terminally bloc ked. The 55- and 58-kDa compounds yielded the same N-terminus, which showed no homology to known proteins in the databases. Conclusion The combination of two independent protein separation techniques , immunoblotting and N-terminal sequencing, identified an N-terminus of two allergens in the 60-kDa molecular weight region. Our data will be helpful for the definite molecular characterization of these important cross-reacti ve molecules.