DIRECT ELECTROCHEMISTRY OF PARSLEY PLASTOCYANIN ON PYROLYTIC-GRAPHITEELECTRODES

A steady quasi-reversible electrochemical response due to parsley plas tocyanin is reported at an edge-plane graphite electrode without the r equirement for so-called adjunct-promoters. This observation is unusua l in that studies involving plastocyanins from other sources require t he addition of polyvalent cations to the solution in order to promote the heterogeneous electron transfer. Here cationic adjunct-promoters a re required only under conditions of low ionic strength, where sigmoid al responses are obtained, characteristic of the presence of a low num ber of electroactive sites on the electrode surface such that conditio ns of radial, as opposed to linear, diffusion apply.