Isolation and purification of plastocyanin from spinach stored frozen using hydrophobic interaction and ion-exchange...

A new simple three-day procedure for preparative isolation and purification of plastocyanin from spinach stored in the frozen state is described. This procedure is based on batch adsorption on ion-exchange resin, ammonium sulphate precipitation, and purification on a Phenyl-Sepharose hydrophobic interaction column and a single Q Sepharose High Performance ion-exchange column. Approximately 100 mg of plastocyanin with an absorbance ratio A278/A597 of 1.10±0.02 in the oxidized state was typically obtained from 12 kg of spinach leaves. The purified spinach plastocyanin is shown to be homogeneous to the resolution of free solution capillary electrophoresis.