Time-resolved spectroelectrochemical techniques for monitoring redox and redox-linked processes in proteins

MURGIDA D. H.

San Pedro

Congreso; I São Paulo Advanced School (ESPCA) on Redox Processes in Biomedicine; 2011

The study of protein electron transfer reactions requires techniques able to monitor not only electron exchange, but also protein dynamics and redox-linked structural changes at the levels of the redox center and of the protein matrix. In this respect, the combination of electrochemical methods with surface-enhanced infrared (SEIRA) and surface-enhanced resonance Raman (SERR) spectroscopic detection represent powerful approaches as they are able to monitor these aspects simultaneously over a wide time scale. In this lecture we will introduce the physicochemical and instrumental basis of these techniques and illustrate their capabilities and limitations based on recent studies by our group on soluble electron shuttle proteins and membrane bound redox enzymes. Specifically, we will discuss the structural determinants that regulate the thermodynamic (E0) and kinetic (, G≠, HDA) parameters of electron transfer reactions in heme, Cu and heme-Cu redox proteins. We will also present results that suggest that biologically relevant electric fields play a crucial role in determining the structure, dynamics and thermodynamics of respiratory redox proteins, thereby constituting the basis of a possible feedback inhibition mechanism for the regulation of ET respiratory chains. Finally, we will show that meaningful electric field are able to control or induce redox-linked conformational changes that represent loss or gain of function, depending on the specific protein.