One-step purification of the beta-glucan elicitor-binding protein from soybean (Glycine max L.) roots and characterization of an anti-peptide antiserum.

A low abundance beta-glucan elicitor-binding protein from soybean was isolated by a rapid, simple and one-step purification method yielding about 9000-fold enrichment. The affinity-based purification technique was more efficient than a procedure that uses conventional methods and preserved the binding activity to a much larger extent. The final preparation consisted of one major protein with an apparent molecular mass of about 75 kDa. Electrophoretic analyses of the purified and photoaffinity-labeled binding protein showed that the native protein was an oligomer with apparent molecular mass of about 240 kDa. A polyclonal anti-peptide antiserum was raised against a synthetic 15-mer internal oligopeptide sequence derived from the 75-kDa protein. The antiserum recognized the purified binding protein in immunoblotting experiments and precipitated the affinity-labeled protein from a crude extract of the membrane fraction.