Two variants of ragweed allergen Ra3.

Two disc electrophoretic forms of Ra3 (I and II) were isolated by column chromatography in yields of 30 and 10 mg/kg pollen, respectively. On the basis of 8% carbohydrate content (determined for Ra3I and assumed for Ra3II), the major and minor forms had essentially identical molecular weights (12,300 daltons). Although their amino acid compositions were similar, a number of single residue differences were found, some of which were confirmed in separate studies on the complete amino acid sequences of Ra3I and Ra3II. In limited assays, no differences were observed in their antigenic and allergenic specificities.