Differential extraction of isoperoxidases from Pisum shoots

When green or etiolated Alaska pea shoots are extracted with water or 50 mM phosphate buffer, pH 6·5, or macerated without addition of buffer, the elution profile of the resulting supernatant lacks several isoperoxidase components which are readily extracted from the residue with 10 mM EDTA at pH 6·5. Subsequent extraction with 270 mM NaCl does not solubilize any further components. These results cast doubt on the validity of earlier reports on isoperoxidase patterns in Pisum and other plants.