In Situ Spectroelectrochemical Investigations of Electrode-Confined Electron-Transferring Proteins and Redox Enzymes.

This perspective analyzes recent advances in the spectroelectrochemical investigation of redox proteins and enzymes immobilized on biocompatible or biomimetic electrode surfaces. Specifically, the article highlights new insights obtained by surface-enhanced resonance Raman (SERR), surface-enhanced infrared absorption (SEIRA), protein film infrared electrochemistry (PFIRE), polarization modulation infrared reflection-absorption spectroscopy (PMIRRAS), Förster resonance energy transfer (FRET), X-ray absorption spectroscopy (XAS), electron paramagnetic resonance (EPR), and differential electrochemical mass spectrometry (DMES)-based spectroelectrochemical methods on the structure, orientation, dynamics, and reaction mechanisms for a variety of immobilized species. This includes small heme and copper electron shuttling proteins, large respiratory complexes, hydrogenases, multicopper oxidases, alcohol dehydrogenases, endonucleases, NO-reductases, and dye decolorizing peroxidases, among other enzymes. Finally, I discuss the challenges and foreseeable future developments toward a better understanding of the functioning of these complex macromolecules and their exploitation in technological devices.