Related Experiment Video
Updated: Jul 9, 2025
10:09
Photobleaching Enables Super-resolution Imaging of the FtsZ Ring in the Cyanobacterium Prochlorococcus
Published on: November 6, 2018
6.3K
Merocyanines form bacteriorhodopsins with strongly bathochromic absorption maxima
Megan J Mackintosh1, Dorothee Hoischen2,3, Hans-Dieter Martin2
1Fritz Haber Center for Molecular Dynamics, Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel.
Summary
Researchers developed novel merocyanine dyes to shift biomolecule absorbance for optogenetics and photo-pharmacology. These synthetic chromophores in bacteriorhodopsin achieved significant red shifts, enhancing fluorescence and reducing Stokes shifts compared to native bacteriorhodopsin.
Area of Science:
- Biophysics
- Photochemistry
- Molecular Biology
Background:
- Biomolecule absorbance needs shifting to the tissue optical transparency window for optogenetics and photo-pharmacology.
- Bacteriorhodopsin (bR) is a light-driven proton pump with a retinal chromophore absorbing at 568 nm.
- Strategies to red-shift absorption maxima are crucial for advanced biological applications.
Purpose of the Study:
- To synthesize merocyanine dyes as retinal replacements in bacteriorhodopsin.
- To achieve a bathochromic shift in absorption maxima for enhanced optical properties.
- To investigate the photophysical properties and structural basis of these novel chromoproteins.
Main Methods:
- Synthesis of 11 merocyanine dyes.
- Assembly of dyes with bacterioopsin (bO) to form chromoproteins.
- Spectroscopic analysis (absorption, fluorescence) of dyes and chromoproteins.
- Quantum chemical calculations (ADC(2), QM/MM) for theoretical validation.
Main Results:
- Stable, covalently bound chromoproteins were formed with significant red-shifted absorbance bands.
- Maximal red shifts were observed for merocyanine dyes 9, 2, and 8, with absorption maxima at 766, 755, and 736 nm, respectively.
- Merocyanine-based chromoproteins exhibited fluorescence quantum yields several orders of magnitude higher and Stokes shifts significantly smaller than native bR.
- Computational methods showed excellent agreement with experimental data and elucidated the origin of the bathochromic shift.
Conclusions:
- Merocyanine dyes can effectively replace retinal in bacteriorhodopsin to achieve substantial red shifts in absorption.
- These novel chromoproteins possess superior fluorescence properties and reduced Stokes shifts compared to native bR.
- The findings provide a foundation for developing advanced photoactive biomolecules for therapeutic and research applications.
Related Concept Videos
01:11Channel Rhodopsins
2.6K
Most organisms use photoreceptors to sense and respond to light. Examples of photoreceptors include bacteriorhodopsins and bacteriophytochromes in some bacteria, phytochromes in plants, and rhodopsins in the photoreceptor cells of the vertebral retina. The light-sensitive property of these receptors is because of the bound chromophores, such as bilin in the phytochromes and retinal in the rhodopsins.
Rhodopsins belong to the family of cell surface proteins called G-protein coupled receptors,...
Rhodopsins belong to the family of cell surface proteins called G-protein coupled receptors,...
2.6K
01:32UV–Vis Spectroscopy of Conjugated Systems
7.0K
Organic compounds with conjugated double bonds show strong absorption features in the UV–visible region of the electromagnetic spectrum attributed to π → π* electronic excitations. Generally, a UV–vis absorption spectrum is recorded as a plot of absorbance vs wavelength. The wavelength of maximum absorbance, which manifests as a peak in the absorption spectrum, is denoted as λmax.
One of the factors influencing λmax is the extent...
One of the factors influencing λmax is the extent...
7.0K
01:29The Photochemical Reaction Center
4.1K
Reaction centers are pigment-protein complexes that initiate energy conversion from photons to chemical entities. Therefore, photochemical reaction center is a more appropriate term that describes these complexes. The Nobel laureates Robert Emerson and William Arnold provided the first experimental evidence of photochemical reaction centers by demonstrating the participation of nearly 2,500 chlorophyll molecules for the release of just one molecule of oxygen. Despite thousands of photosynthetic...
4.1K
01:11Aryldiazonium Salts to Azo Dyes: Diazo Coupling
2.9K
The reaction of weakly electrophilic aryldiazonium (also called arenediazonium) salts with highly activated aromatic compounds leads to the formation of products with an —N=N— link, called an azo linkage. This reaction, presented in Figure 1, is known as diazo coupling and occurs without the loss of the nitrogen atoms of the aryldiazonium salt. Highly activated aromatic compounds such as phenols or arylamines favor the diazo coupling reaction. The coupling generally occurs at the...
2.9K
03:02Colors and Magnetism
11.7K
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
11.7K
01:22Photoreceptors and Visual Pathways
6.0K
At the molecular level, visual signals trigger transformations in photopigment molecules, resulting in changes in the photoreceptor cell's membrane potential. The photon's energy level is denoted by its wavelength, with each specific wavelength of visible light associated with a distinct color. The spectral range of visible light, classified as electromagnetic radiation, spans from 380 to 720 nm. Electromagnetic radiation wavelengths exceeding 720 nm fall under the infrared category,...
6.0K