ISOLATION OF GIBBERELLIN-BINDING PROTEINS BY AFFINITY-CHROMATOGRAPHY

Gibberellin-binding proteins (GBPs) were isolated from a crude extract of etiolated maize seedlings by affinity chromatography on gibberellin A(3)(GA(3))-linked enhance-aminohexyl(EAH)-Sepharose 4B. The isolated proteins had a binding activity for [H-3]-GA(4). The binding site with dissociation constant of 0.5 mu M for GA(4) was detected in the proteins by the binding assay with the procedures of ammonium sulfate precipitation. The binding of [H-3]-GA(4) to GBPs was reversible and could be inhibited by the addition of GA(1) and GA(3). An inactive gibberellin, GA(13), had no inhibitory effect on the binding of [H-3]-GA(4) to GBPs.