Partial Purification and Characterization of Copper-binding Protein from Roots of Agrostis gigantea Roth

A Cu-binding protein was isolated from roots of the grass Agrostis gigantea Roth. Heat stable proteins were chromatographed on the strongly basic anion exchanger QAE-Sephadex A-25. Dark brown pigments were retained by the ion exchanger during elution of Cu-binding protein. Further purification was achieved by gel filtration on Bio-Gel P-6 in buffer containing 1 kmol m(-1) KCl. The resulting protein was a light blue powder; had an apparent molecular weight of 1700; contained 11% cys, 14% asp, 27% glu and 0.25g atoms Cu per mol; the Cu : cysteine ratio was 1:6. No Cu(I) typical of Cu(I)-thiolate bonds of Cu-thionein was found despite taking precautions to prevent Cu oxidation.