📘 Conformational transitions of proteins play a crucial role in many biochemical and biophysical reactions. Understanding the conformational changes of a protein upon adsorption to a substrate is very important in biotechnology, e.g. the development of modern protein chip technology, biocompatibility of implants, and many other ones. This research program used cytochrome c, an electron carrier in the respiratory chain, as a model to probe how surface adsorption affects the folding of a protein. My work investigates the interaction of protein horse heart cytochrome c when it is electrostatically adsorbed or covalently attached onto a 1 nm thick monolayer film, which covers an Au surface. After changing the pH value of the solutions or adding the denaturants into the solutions, the conformation of cytochrome c changes and causes a change of the peak current of cyclic voltammgram. In addition, the denatured cytochrome c's peroxidase activity will be studied and compared with the peroxidase activity of microperoxidase-11.