THE DIRECT ELECTROCHEMISTRY OF CYTOCHROME-C IN THE PRESENCE OF VARIOUS AMINO-ACIDS

The promotion of horse heart cytochrome c electrochemistry at a gold m inigrid electrode in the presence of some amino acids in solution has been investigated by cyclic voltammetry. Of these, Cys, His, Met, Cia and Trp have proved to be effective in facilitating electron transfer between Cyt c and the gold electrode, and good, quasi-reversible redox reactions were achieved. Under alkaline pH conditions, the above amin o acids also present a promotion effect on the electrochemistry of Cyt c, but a different cyclic voltammogram appears. The new appearance re sults from the stability of different conformation states of Cyt c at different pH regions. Trp shows a more pH dependent ability in promoti ng the electrochemistry of Cyt c at a gold electrode. Probably, the pr oton dissociation and steric factor of the bulky indole group account for its electrochemical behavior. The spectroelectrochemistry of cytoc hrome c in the presence of various amino acids has also been examined.