Several redox proteins are studied at Nafion-coated pyrolytic graphite
(PG) electrodes. electrochemical behavior of polyheme c-type cytochro
mes and spinach ferredoxin is described using cyclic and square-wave v
oltammetry (SWV). No signals are detected when Nafion-coated electrode
s are exposed to the protein solutions. In contrast, electrochemical r
esponses are observed when droplets of protein solutions, deposited on
the PG surface are dried then entrapped in Nafion layer. These Nafion
-modified electrodes permit one to detect very small amounts (1 mug) o
f cytochrome c3. The stability of entrapped molecules upon repetitive
cycling has been investigated. Such modified electrodes offer new pers
pectives for studying proteins confined at electrode surfaces.