Photobiology articles within Nature Chemistry

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  • Article
    | Open Access

    Pump–probe measurements conventionally achieve femtosecond time resolution for X-ray crystallography of reactive processes, but the measured structural dynamics are complex. Using coherent control techniques, we show that the ultrafast crystallographic differences of a fluorescent protein are dominated by ground-state vibrational processes that are unconnected to the photoisomerization reaction of the chromophore.

    • Christopher D. M. Hutchison
    • , James M. Baxter
    •  & Jasper J. van Thor

  • Article |

    Acylhydrazones are often found in compounds across screening databases, and numerous bioactive acylhydrazones exist. This functional group can isomerize between E and Z in response to light or upon exposure to thiols. Now, E/Z isomerization is found to impact activities of bioactive acylhydrazones and should be routinely analysed.

    • Zhiwei Zhang
    • , Giang N. T. Le
    •  & G. Andrew Woolley

  • Article
    | Open Access

    The metallophilic interaction between cyclometalated palladium complexes can facilitate supramolecular nanostructure formation in living mice, providing a phototoxic prodrug with a long circulation time and high tumour-targeting efficiency. Upon green light irradiation, this palladium-based drug destroys solid tumours, leaving non-irradiated organs intact.

    • Xue-Quan Zhou
    • , Peiyuan Wang
    •  & Sylvestre Bonnet

  • Article |

    A genetically encoded phototrigger based on a xanthone amino acid can expand the scope of time-resolved serial femtosecond crystallography beyond naturally photoactive proteins. This approach has been used to uncover metastable reaction intermediates that occur prior to C–H bond activation in a human liver fatty-acid-binding protein mutant.

    • Xiaohong Liu
    • , Pengcheng Liu
    •  & Jiangyun Wang

  • Article |

    Developing stimuli-responsive bioorthogonal tetrazine ligations remains highly challenging, but a versatile approach that uses photocaged dihydrotetrazines has now been developed. Photouncaging results in the spontaneous formation of reactive tetrazines that rapidly react with dienophiles such as trans-cyclooctenes. As a demonstration, the method was used for live-cell labelling with single-cell precision and light-triggered drug delivery.

    • Luping Liu
    • , Dongyang Zhang
    •  & Neal K. Devaraj

  • Article |

    Rhodopsin activation is driven by an ultrafast double-bond isomerization, but questions remain about the origin of its sensitivity. Now, quantum–classical simulations show that, 15 fs after light absorption, a degeneracy between the reactive excited state and a neighbouring state causes the splitting of the rhodopsin population into subpopulations, which propagate with different velocities, leading to distinct contributions to the quantum efficiency.

    • Xuchun Yang
    • , Madushanka Manathunga
    •  & Massimo Olivucci

  • Article |

    Voltage imaging is a powerful technique for studying electrical signalling in neurons. A palette of bright and sensitive voltage indicators has now been developed via enzyme-mediated ligation and Diels–Alder cycloaddition. Among these, a far-red indicator faithfully reports neuronal action potential dynamics with an excitation spectrum orthogonal to optogenetic actuators and green/red-emitting biosensors.

    • Shuzhang Liu
    • , Chang Lin
    •  & Peng Zou

  • Article |

    Understanding the mechanism of photoconversion in fluorescent proteins is essential to optimizing applications in imaging and optogenetics. It has now been demonstrated that photoconversion in the photoswitchable protein dronpa follows a multi-step mechanism, with both chromophore and protein structural dynamics occurring on multiple timescales from picoseconds to hundreds of microseconds.

    • Sergey P. Laptenok
    • , Agnieszka A. Gil
    •  & Stephen R. Meech

  • Article |

    Isotope effects provide deep insight into mechanisms of chemical and biochemical processes. Now, it has been shown that the pattern of isotopic substitution of the isomerizing bond of the retinal chromophore in the visual pigment rhodopsin significantly alters the reaction quantum yield—revealing a vibrational phase-dependent isotope effect.

    • C. Schnedermann
    • , X. Yang
    •  & R. A. Mathies

  • Article |

    Providing detailed structural descriptions of the ultrafast photochemical events that occur in light-sensitive proteins is key to their understanding. Now, excited-state structures in the reversibly switchable fluorescent protein rsEGFP2 have been solved by time-resolved crystallography using an X-ray laser. These structures enabled the design of a mutant with improved photoswitching quantum yields.

    • Nicolas Coquelle
    • , Michel Sliwa
    •  & Martin Weik

  • News & Views |

    The flow of energy in Earth's primary light harvesters — photosynthetic pigment–protein complexes — needs to be heavily regulated, as the sun's energy supply can vary over many orders of magnitude. Observing hundreds of individual light-harvesting complexes has now provided important insights into the machinery that regulates this process.

    • Peter J. Walla

  • News & Views |

    The process of electronic energy transfer between molecules has long fascinated chemists. Femtosecond spectroscopy measurements of a series of molecular dimers now reveal signals that arise from non-Born–Oppenheimer coupling, suggesting a new mechanism to enhance energy transfer.

    • Daniel B. Turner

  • Article |

    Synthetic heterodimers provide a platform to demonstrate molecular design principles of vibronic coupling. Now, it has been shown that quantum beating caused by vibronic coupling can be controlled by packing a structurally flexible heterodimer on single-walled carbon nanotubes. This quantum beating requires a vibration to be resonant with the energy gap between excited states and structural rigidity.

    • Lili Wang
    • , Graham B. Griffin
    •  & Gregory S. Engel

  • Article |

    Photoreceptors play an essential role in determining the fate of subsequent biological reactions, however, tracking their structural evolution on ultrafast timescales has been challenging. Now, photoactive yellow protein has been studied using time-domain Raman spectroscopy with sub-7-femtosecond pulses, revealing the ultrafast rearrangement of its hydrogen-bonding structure and also the structure of the first photocycle intermediate.

    • Hikaru Kuramochi
    • , Satoshi Takeuchi
    •  & Tahei Tahara

  • News & Views |

    Vision is initiated by photoisomerization of 11-cis retinal in the visual pigment rhodopsin — a fast and efficient process. Spectroscopic studies now demonstrate that the transition from the reactant photoexcited-state to the ground-state photoproduct, which mediates this important reaction, occurs on a sub-50-fs timescale and is vibrationally coherent.

    • Richard A. Mathies

  • Article |

    The isomerization of the retinal chromophore of rhodopsin is the photochemical process that initiates the sense of vision. Now, heterodyne-detected transient grating spectroscopy has been used to resolve coherent vibrational dynamics during this process, helping to identify strictly local vibrational motions as the origin of the coherent surface crossing, which occurs on a sub-50-fs timescale.

    • Philip J. M. Johnson
    • , Alexei Halpin
    •  & R. J. Dwayne Miller

  • Article |

    Photoswitching of phytochromes is based on the isomerization of the tetrapyrrole chromophore, and eventually leads to the (de)activation of an enzymatic output module. Now it has been shown that both the structural changes associated with photoswitching and the thermal decay of the light-activated state are coupled to proton translocations in the chromophore pocket.

    • Francisco Velazquez Escobar
    • , Patrick Piwowarski
    •  & Peter Hildebrandt

  • Article |

    Amiloride is a widely used diuretic that blocks epithelial sodium channels (ENaCs); however, the functional role of the different ENaC isoforms is still poorly understood and no pharmacological tools exist to differentiate between them. Now, photoswitchable amilorides that enable the optical control of ENaCs, and can distinguish between different ENaC isoforms have been developed.

    • Matthias Schönberger
    • , Mike Althaus
    •  & Dirk Trauner

  • News & Views |

    Biological solar energy conversion requires the coordinated and rapid movement of protons and electrons through complex proteins, called reaction centres. Now, an artificial and structurally simple reaction centre has been synthesized that mimics an important, photosynthetic charge relay.

    • Bridgette A. Barry

  • Article |

    An artificial reaction centre has been designed that contains a benzimidazole–phenol model of the Tyr–His relay in photosystem II. It has been seen to mimic both the short internal hydrogen bond of the natural relay, and — using electron paramagnetic resonance —the relaxation behaviour that accompanies proton-coupled electron transfer in photosystem II.

    • Jackson D. Megiatto Jr
    • , Dalvin D. Méndez-Hernández
    •  & Ana L. Moore

  • Article |

    Quantum coherence has been observed in the major light-harvesting complex of photosystem II (LHCII) from green plants. By controlling the laser pulse polarization in two-dimensional electronic spectroscopy, signals from quantum coherence have been separated from other molecular processes, offering insight into the role of quantum coherence in photosynthetic light-harvesting.

    • Gabriela S. Schlau-Cohen
    • , Akihito Ishizaki
    •  & Graham R. Fleming

  • News & Views |

    The chemical introduction of a photoswitchable ligand into ion channel structures should make it possible to study the diverse roles of neurotransmitters and receptors in the brain.

    • G. Andrew Woolley

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