A FRET-based method to study the activity of electron or oxygen transfer proteins and redox enzymes

This thesis centers around a novel fluorescence based method that allows to monitor the activity of redox enzymes and of electron (ET) or oxygen transfer proteins. It takes advantage of the fact that the absorption spectrum of the protein__s active site varies upon changing its redox state. This change can be translated into a change in the fluorescence intensity of a label that is covalently linked to the protein on the basis of F_rster Resonance Energy Transfer (FRET). With our method we could show that different redox proteins and enzymes can be studied down to the single molecule level. This exciting finding opens the door to the study of various redox enzymes and to monitor specific substances such as for example nitrite. Depending on the function of the enzyme under investigation a wide range of substrates can be monitored. Another example is the development of an oxygen sensor by employing proteins that are capable of binding oxygen. The findings presented in this thesis might be significant for applications in oxygen sensing and, more generally, in the fast growing field of biosensin