Voltammetric Studies of Spinach Ferredoxin on a Glassy Carbon Electrode Modified with Cobalt(II) Tetrasulfophthalocyanine

Spinach ferredoxin has been studied electrochemically at a glassy carbon electrode (GCE) modified with cobalt(II) tetrasulfophthalocyanine ([Co(II)TSPc]4−). Anodic peak currents due to the oxidation of the cysteine component of ferredoxin were observed at 0.90 V (vs. Ag/AgCl) (pH 7.4, HEPES buffer). The magnitudes of the peak currents were dependent on pH. Catalytic oxidation of ferredoxin was also observed when the GCE was modified with cobalt(II) and oxomolybdenum(V) phthalocyanine [CoPc and OMo(OH)Pc, respectively], and with copper(II) tetrasulfophthalocyanine complexes ([Cu(II)TSPc]4−).