The usefulness of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) could be shown in order to demonstrate various stages of structural damage in selected parchment samples. As a consequence experiments were carried out to simulate the action of copper pigments on parchment structure in the course of aging under controlled environment. Copper (II) acetate as well as copper (II) sulfate were applied. It could be shown that, most probably as the primary step of degradation, conformational change, i.e. unfolding of the protein chains, is induced by the action of copper(II)-ions. Generally, this change results in higher electrophoretic mobilities of all components observed. It is concluded that much longer aging would be required to bring about structural damage similar to that of samples from original objects of art.