Electrochemical behaviour of cytochrome c at low potentials

d.c. polarograms of bovine heart cytochrome c show reduction currents at low potentials. This is observed in buffer solutions with pH values between 1 and 10.5. These currents are attributed to catalytic hydrogen formation (pre-sodium currents). After succinylation of the protein, the current in glycine-NaOH buffer of pH 10.5 disappears almost completely, whereas that in acetate buffer of pH 4.5 is affected only slightly. It is concluded that different groups are responsible for the currents observed in these two buffer