Mechanism of the Initial Conformational Transition of a Photomodulable Peptide

A biomimetic molecular switch at work: coupling photoisomerization dynamics to peptide structural rearrangement

A combined experimental and computational study of a peptide-linked retinal-like molecular switch shows the effects on photoreactivity and the α-helix structure.

Hydantoin-based molecular photoswitches

A new family of molecular photoswitches based on arylidenehydantoins is described together with their synthesis and photochemical and photophysical studies. A series of hydantoin derivatives have been prepared as single isomers using simple and versatile chemistry in good yields. Our studies show that the photostationary states of these compounds can be easily controlled by means of external factors, such as the light source or filters. Moreover, the detailed investigations proved that these switches are efficient (i.e., they make efficient use of the light energy, are high fatigue resistant, and are very photostable). In some cases, the switches can be completely turned on/off, a desirable feature for specific applications. A series of theoretical calculations have also been carried out to understand the photoisomerization mechanism at the molecular level.

Benzylidene-oxazolones as molecular photoswitches

The synthesis and photochemical study of a family of molecular switches inspired by the green fluorescent protein (GFP) chromophore is presented. These compounds can be easily synthesized, and their photophysical properties may be tuned. Due to their efficient photoisomerization and high stability, these compounds can be switched on/off by using light and heat or light with different wavelengths.

Reversible photocontrol of peptide conformation with a rhodopsin-like photoswitch

Reversible photocontrol of biomolecules requires chromophores that can efficiently undergo large conformational changes upon exposure to wavelengths of light that are compatible with living systems. We designed a benzylidene-pyrroline chromophore that mimics the Schiff base of rhodopsin and can be used to introduce light-switchable intramolecular cross-links in peptides and proteins. This new class of photoswitch undergoes an ~10 Å change in end-to-end distance upon isomerization and can be used to control the conformation of a target peptide efficiently and reversibly using, alternately, violet (400 nm) and blue (446 nm) light.

Infrared Studies of Small Azobenzene Peptides: Unexpectedly Slow Reactions on the Time Range of Minutes

Infrared absorption experiments on light-triggered azobenzene peptides have been performed below and above the freezing point of the solvent dimethyl sulfoxide (DMSO). Even 20 K below the freezing point, illumination of the azobenzene chromophore resulted in IR absorption changes indicative of light-induced structural rearrangements of the peptide. In addition, new conformational states could be found at low temperature, which involve the formation of additional hydrogen bonds. In one sample the new low-temperature state survived melting and reheating and disappeared at 298 K only on the time scale of 10 min. The observations indicate that at low temperatures the peptide, together with traces of water present in the sample, forms a shell in the vicinity of the chromophore that facilitates internal motion even in the rigid cage of frozen DMSO.