Infrared Spectroscopic and Electrochemical Approaches for the Study of the Reaction Mechanism of Immobilized Membrane Proteins from the Respiratory Chain

Abstract

Although the architectures of several membrane proteins in respiration as well as the basic chemical reactions have been described, the interactions on molecular level, the high diversity and the high efficiency of mechanisms, are under discussion. Experiments have been developed which reveal how protons and other ions are drawn through proteins and how they are coupled to electron transfer.An electrochemical approach on proteins immobilized on gold nano particles was used to get insight into the redox properties in the presence and absence of substrate and inhibitors to the proton channels (Zn2+).1 Two approaches are presented to functionally probe the enzymes against substrates and inhibitors: i) The redox reaction was IR spectroscopically studied in solution and ii) the proteins are immobilized via their His-Tag on a gold layer, deposited on an ATR-crystal and studied by surface enhanced IR spectroscopy (SEIRAS). 2 The combination of the electrochemical and IR spectroscopic approach allowed the observation of protein action at the level of single functional groups within the large protein studied and thus provides essential knowledge's for the understanding of the mechanism of the studied enzymes.