Related Experiment Video
Updated: Jul 11, 2025
10:03
Proton Transfer and Protein Conformation Dynamics in Photosensitive Proteins by Time-resolved Step-scan Fourier-transform Infrared Spectroscopy
Published on: June 27, 2014
18.0K
Two-Dimensional Electronic Spectroscopy of the Far-Red-Light Photosystem II Reaction Center
Yogita Silori1, Rhiannon Willow1, Hoang H Nguyen1
1Department of Physics and Biophysics, University of Michigan, 450 Church Street, Ann Arbor, Michigan 48109, United States.
The Journal of Physical Chemistry Letters
|November 9, 2023
Summary
Researchers studied photosystem II (PSII) using cyanobacteria grown in far-red light. Primary charge separation was found to occur between ChlD1 and PD1, challenging previous models of PSII function.
Area of Science:
- Photosynthesis research
- Biophysics
- Cyanobacterial biology
Background:
- Spectral overlap of pigments in photosystem II (PSII) hinders understanding of primary energy conversion.
- Cyanobacteria grown in far-red light incorporate chlorophyll-f and chlorophyll-d, potentially resolving spectral congestion.
Purpose of the Study:
- Investigate the primary charge separation mechanism in far-red light-grown PSII (FRL-PSII).
- Determine the role of specific chlorophyll pigments in FRL-PSII energy conversion.
Main Methods:
- Two-dimensional electronic spectroscopy at 77 K.
- Analysis of Synechococcus sp. PCC 7335 cells grown in far-red light.
Main Results:
- Observed formation of a ChlD1•−PD1•+ radical pair within ~3 ps.
- Found no evidence for PheoD1 involvement as the primary electron acceptor in FRL-PSII.
- Attributed the lack of PheoD1 involvement to dithionite treatment.
Conclusions:
- Primary charge separation in FRL-PSII occurs between ChlD1 and PD1.
- The P D1/P D2 heterodimer may play a significant, underappreciated role in PSII charge separation.
- This finding offers new insights into the adaptability and mechanisms of photosynthesis.
More Related Videos
Related Concept Videos
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
01:22Photosystem II
70.7K
The multi-protein complex photosystem II (PS II) harvests photons and transfers their energy through its bound pigments to its reaction center, and ultimately to photosystem I (PSI) through the electron transport chain. The pigments responsible for caputirng the light energy in photosystems include chlorophyll a, chlorophyll b, and carotenoids.
The pigment molecules are arranged across two photosystem domains — the antenna complex and the reaction center. The main aim of the pigment...
The pigment molecules are arranged across two photosystem domains — the antenna complex and the reaction center. The main aim of the pigment...
70.7K
01:42The Antenna Complex
6.0K
Plants and other photosynthetic organisms comprise pigments capable of absorption of direct sunlight. These pigments are present in the reaction center - the main site of photochemical reactions as well as in the antenna complex. Under average light conditions, the rate at which reaction center pigments absorb light is far below the electron transport chain's capacity. As a result, the reaction center alone cannot provide enough energy to drive photosynthesis. The photosynthetic efficiency...
6.0K
01:34The Z-Scheme of Electron Transport in Photosynthesis
10.2K
The light reactions of photosynthesis assume a linear flow of electrons from water to NADP+. During this process, light energy drives the splitting of water molecules to produce oxygen. However, oxidation of water molecules is a thermodynamically unfavorable reaction and requires a strong oxidizing agent. This is accomplished by the first product of light reactions: oxidized P680 (or P680+), the most powerful oxidizing agent known in biology. The oxidized P680 that acquires an electron from the...
10.2K
01:32UV–Vis Spectroscopy of Conjugated Systems
7.1K
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...
7.1K
01:16UV–Vis Spectroscopy: Molecular Electronic Transitions
1.6K
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...
1.6K