Related Experiment Video
Updated: May 2, 2026
09:57
Ultrafast Time-resolved Near-IR Stimulated Raman Measurements of Functional π-conjugate Systems
Published on: February 10, 2020
7.1K
Excited-State Mixing in the LOV Domain Proteins: Possible Physics behind the Difference in the Transient Absorption
Yingliang Liu1,2,3, Aditya S Chaudhari1, Alessandra Picchiotti2,4
1Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Průmyslová 595, CZ-252 50 Vestec, Czechia.
The Journal of Physical Chemistry Letters
|April 16, 2025
Summary
Excited electronic state mixing in flavin mononucleotide (FMN) within light-oxygen-voltage-sensing (LOV) domains is investigated. Binding to EL222 induces spectral changes, suggesting electronic state mixing influenced by hydrogen bonding.
Area of Science:
- Photochemistry
- Biophysics
- Spectroscopy
Background:
- Light-oxygen-voltage-sensing (LOV) domains are crucial photoreceptors.
- The role of excited electronic state mixing in flavin cofactors within LOV domains is not fully understood.
- Flavin mononucleotide (FMN) is the common cofactor in LOV domains.
Purpose of the Study:
- To investigate excited electronic state mixing in FMN upon binding to the EL222 LOV domain.
- To elucidate the influence of protein environment on FMN electronic states.
Main Methods:
- Transient absorption spectroscopy of free and EL222-bound FMN.
- Femtosecond stimulated Raman spectroscopy (FSRS) of free and EL222-bound FMN.
- Analysis of spectral changes in the excited state (S1).
Main Results:
- Observed changes in the excited-state absorption spectrum around 800 nm upon FMN binding to EL222.
- Detected relative intensity increase in specific vibrational modes (N1-C2 and C2═O2 stretching) in the S1 state Raman spectra.
- Correlated spectral changes with previously calculated geometric differences between ππ* and nπ* states.
Conclusions:
- Proposed probable electronic state mixing in EL222-bound FMN.
- Identified asymmetric hydrogen bonding at the flavin O4 atom and reduced hydrogen bonding at the O2 atom as factors favoring this mixing.
- The protein environment of the LOV domain significantly influences the electronic properties of the FMN cofactor.
Related Concept Videos
01:02¹H NMR: Interpreting Distorted and Overlapping Signals
1.3K
Spin systems where the difference in chemical shifts of the coupled nuclei is greater than ten times J are called first-order spin systems. These nuclei are weakly coupled, and their chemical shifts and coupling constant can generally be estimated from the well-separated signals in the spectrum.
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are...
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are...
1.3K
01:14Molecular Spectroscopy: Absorption and Emission
4.1K
Molecules possess discrete energy levels called quantum states. Unlike atoms, which have simpler energy levels, molecules possess additional rotational and vibrational energy levels. Each energy level is separated by an energy gap, with the gaps between adjacent electronic, vibrational, and rotational levels varying significantly. The three types of energy levels in a diatomic molecule are shown in Figure 1.
4.1K
01:16UV–Vis Spectroscopy: Molecular Electronic Transitions
3.0K
In Ultraviolet–Visible (UV–Vis) spectroscopy, the absorption of electromagnetic radiation is used to probe the electronic structure of molecules. This technique provides insights into molecular electronic transitions, particularly the movement of electrons between different molecular orbitals. Radiation is absorbed if the energy of the electromagnetic radiation passing through the molecule is precisely equal to the energy difference between the excited and ground states. During this...
3.0K
01:25Deactivation Processes: Jablonski Diagram
2.3K
Luminescence, the emission of light by a substance that has absorbed energy, is a process that involves the interaction of molecules with light. The energy-level diagram, or Jablonski diagram, is a graphical representation of these interactions, illustrating the various states and transitions a molecule can undergo. In a typical Jablonski diagram, the lowest horizontal line represents the ground-state energy of the molecule, which is usually a singlet state. This state represents the energies...
2.3K
01:20Raman Spectroscopy: Overview
2.6K
The underlying principle of Raman spectroscopy is based on the interaction between light and matter, specifically molecules' inelastic scattering of photons. When a monochromatic beam of light, typically from a laser source, interacts with a sample, most scattered light has the same frequency as the incident light. This is known as Rayleigh scattering.
However, a small fraction of the scattered light exhibits a frequency shift due to the exchange of energy between the incident photons and...
However, a small fraction of the scattered light exhibits a frequency shift due to the exchange of energy between the incident photons and...
2.6K
01:26Raman Spectroscopy Instrumentation: Overview
1.8K
A conventional Raman spectrophotometer includes a laser source, a sample holding system, a wavelength selector, and a detector.
The monochromatic laser source, typically using visible or near-infrared radiation, generates a highly focused beam of light. This light interacts with the molecules of the sample, scattering some of the light. Liquid and gaseous samples are usually tested in ordinary glass capillaries, while solids can be analyzed as powders packed in capillaries or as potassium...
The monochromatic laser source, typically using visible or near-infrared radiation, generates a highly focused beam of light. This light interacts with the molecules of the sample, scattering some of the light. Liquid and gaseous samples are usually tested in ordinary glass capillaries, while solids can be analyzed as powders packed in capillaries or as potassium...
1.8K