Photoswitches

Fast infrared spectroscopy of protein dynamics: advancing sensitivity and selectivity

“…The protein should have only one of these amino acids at the desired position, and in this regard, Met is advantageous as it is relatively rare in natural proteins, whereas His is often crucial for their function. Note that we have disregarded cysteine as another possible anchor point for a label [29], since we want to keep that amino acid free for adding other functionalities, such as a photoswitch [6,8,12,13,59] used to initiate a non-equilibrium process (see the example highlighted below). We reiterate that being able to initiate a non-equilibrium process is a prerequisite to extend the accessible time window beyond the vibrational lifetime of the label.…”

“…As an approach to study its dynamics, Fig. 4a shows a PDZ2 domain with an azobenzene-derivative covalently linked across its binding groove [59] in such a way that photo-isomerization of the linker induces a conformational transition of the protein, which mimics that after ligand binding [12]. By chance, one vibrational mode localized on the azobenzene linker could be spectroscopically isolated in this case (Fig.…”