Electrochemical determination of hydrogen peroxide using Rhodobacter capsulatus cytochrome c peroxidase at a gold electrode

We describe the redox behaviour of horse heart cytochrome c (HHC) and Rhodobacter capsulatus cytochrome c peroxidase (RcCCP) at a gold electrode modified with 4,4?-bipyridyl. RcCCP shows no additional oxidation or reduction peaks compared to the electrochemistry of only HHC, which indicates that it most likely binds to HHC and results in a potential downshift of the voltammetric signals of the latter. Furthermore, the electrochemical determination of hydrogen peroxide at a RcCCP/HHC modified gold electrode is shown. The results demonstrate that HHC can substitute for cytochrome c 2, the physiological electron donor. The buffer 2-[4-(2-hydroxyethyl)-piperazinyl]?ethanesulfonic acid (HEPES) and tris(hydroxymethyl) methylamine (Tris) electrochemically are not as inert as previously believed. They can react with oxygen (radicals) during electrochemical measurements, and the products formed can give rise to additional redox peaks. We therefore also have conducted a voltammetric study on theses buffers.Kavli Institute of NanoscienceApplied Science