PURIFICATION AND CHARACTERIZATION OF ALT A-29 FROM ALTERNARIA-ALTERNATA

A major protein component reactive with pooled human atopic sera was i solated from a lyophilized broth extract of Alternaria alternata 34-01 6. By successive chromatography on Whatman DE-52, Sephadex G-100 and M ono Q HR5/5, a low molecular weight antigen was obtained. Comparison w ith standard proteins on Sephadex G-100 indicated its molecular weight was 31 kD. Non-reduced samples run on SDS-PAGE showed a band at 29.2 kD which reacted strongly with human IgE. After reduction, it produced a doublet pattern on SDS-PAGE with MW 14.5 and 16.0 kD. The doublet p attern was confirmed by Western blotting with pooled human atopic sera . IEF of the protein showed a major component with a PI of 4.15 and tw o minor components at 4.25 and 4.40. Immunoblots of the IEF bands show ed all three were reactive with human IgE. Ion exchange chromatography of the protein on Mono Q HR5/5 resulted in three resolved components, all of which are immunoreactive. Together with the IEF data, this sug gests that there are several conformational or structural isoforms of this protein.