Reply to “Comment on ‘Transient Conformational Changes of Sensory Rhodopsin II Investigated by Vibrational Stark Effect Probes’”

Good Vibrations Report on the DNA Quadruplex Binding of an Excited State Amplified Ruthenium Polypyridyl IR Probe

“…IR probes are powerful molecular tools that, through the phenomenon known as the Vibrational Stark Effect (VSE), have been used to monitor the local environment in chemically important processes. , The nitrile stretching vibration is sensitive to its local electrostatic environment, and it is possible to exploit the fact that different solvents exert different “effective” electric fields on the probe, which result in a shift in the position of the frequency of the nitrile band. , Nitrile probes are also sensitive to the hydrogen bonding (HB) environment accessed in DMSO/water mixtures . The sensitivity of the nitrile vibration to changes in the electrostatic field, together with the location of its vibration in a distinct IR window, has made it a particularly attractive probe to characterize complex molecular environments, , and this has been used to characterize proteins, conformational changes in sensory Rhodopsin II, , enzyme active sites, lipid membranes, and nucleic acids . Nitrile probes have also been used to quantify the effect of changing electric fields on the enzyme active site by monitoring the magnitude of the electrostatic perturbation introduced by photoexcitation of a fluorescent analogue of the reaction intermediate .…”

“… 63 , 64 Nitrile probes are also sensitive to the hydrogen bonding (HB) environment accessed in DMSO/water mixtures. 65 The sensitivity of the nitrile vibration to changes in the electrostatic field, together with the location of its vibration in a distinct IR window, has made it a particularly attractive probe to characterize complex molecular environments, 66 , 67 and this has been used to characterize proteins, 68 conformational changes in sensory Rhodopsin II, 69 , 70 enzyme active sites, 71 lipid membranes, 72 and nucleic acids. 73 Nitrile probes have also been used to quantify the effect of changing electric fields on the enzyme active site by monitoring the magnitude of the electrostatic perturbation introduced by photoexcitation of a fluorescent analogue of the reaction intermediate.…”