Purification, characterization, and partial sequencing of two new allergens of Olea europaea

Background: The inhalation of olive (Olea europaea) pollen is an important cause of allergic respiratory diseases in southern Europe and California. Objective: The aims of this study were to characterize the allergenic composition of O. europaea pollen collected in California and to purify two important allergens. Methods: One hundred grams of O. europaea pollen was extracted dialyzed in 10 kd cut-off membranes and lyophilized. Allergen characterization was done by sodium dodecylsulfate-polyacrylamide gel electrophoresis and immunoblotting. Two allergens were isolated by gel filtration, ion exchange, and hydrophobic interaction chromatography and sequenced. Results: Ole e 4 has an apparent molecular weight, under reducing conditions, of 32 kd and pIs between 4.65 and 5.1. The N-terminal was blocked and the analysis of the amino acid sequence of two internal regions revealed no homology with other known proteins. Ole e 5 has a molecular weight of 16 kd and pIs between 5.1 and 6.5. The amino acid sequence of the N-terminal showed a high degree of homology with superoxide dismutase of several plant species. Ole e 4 and Ole e 5 had an IgE binding frequency by immunoblot of 80% and 35%, respectively. Conclusions: Olive pollen extracts have a heterogeneous composition, with several important allergens. One of these allergens showed a high degree of homology with a superoxide dismutase.