Carbon−Deuterium Bonds as Site-Specific and Nonperturbative Probes for Time-Resolved Studies of Protein Dynamics and Folding

Carbon−deuterium (C−D) bonds are nonperturbative spectroscopic probes that absorb in a region of the IR spectrum that is free of other protein absorptions. We explore the use of these probes under time-resolved conditions to follow the unfolding of cytochrome c from a photostationary state that accumulates after CO is photodissociated from the protein’s heme prosthetic group. Our results clearly show that C−D bonds are well-suited to characterize protein folding and dynamics.