Uphill Energy Trapping by Reaction Center in Bacterial Photosynthesis:  Charge Separation Unistep from Antenna Excitation, Virtually Mediated by Special-Pair Excitation

2002 ◽  
Vol 106 (51) ◽  
pp. 13370-13383 ◽  
Author(s):  
Hitoshi Sumi
Keyword(s):  
Reaction Center ◽  
Charge Separation ◽  
Bacterial Photosynthesis ◽  
Energy Trapping ◽  
Special Pair ◽  
Pair Excitation

scholarly journals Primary processes in the bacterial reaction center probed by two-dimensional electronic spectroscopy

2018 ◽  
Vol 115 (14) ◽  
pp. 3563-3568 ◽  
Author(s):  
Andrew Niedringhaus ◽  
Veronica R. Policht ◽  
Riley Sechrist ◽  
Arkaprabha Konar ◽  
Philip D. Laible ◽  
...  
Keyword(s):  
Excited State ◽  
Reaction Center ◽  
Charge Separation ◽  
Purple Bacteria ◽  
Electronic Spectroscopy ◽  
Reaction Centers ◽  
Purple Bacterium ◽  
Absorption Bands ◽  
Sequential Reaction ◽  
Special Pair

In the initial steps of photosynthesis, reaction centers convert solar energy to stable charge-separated states with near-unity quantum efficiency. The reaction center from purple bacteria remains an important model system for probing the structure–function relationship and understanding mechanisms of photosynthetic charge separation. Here we perform 2D electronic spectroscopy (2DES) on bacterial reaction centers (BRCs) from two mutants of the purple bacterium Rhodobacter capsulatus, spanning the Qy absorption bands of the BRC. We analyze the 2DES data using a multiexcitation global-fitting approach that employs a common set of basis spectra for all excitation frequencies, incorporating inputs from the linear absorption spectrum and the BRC structure. We extract the exciton energies, resolving the previously hidden upper exciton state of the special pair. We show that the time-dependent 2DES data are well-represented by a two-step sequential reaction scheme in which charge separation proceeds from the excited state of the special pair (P*) to P+HA− via the intermediate P+BA−. When inhomogeneous broadening and Stark shifts of the B* band are taken into account we can adequately describe the 2DES data without the need to introduce a second charge-separation pathway originating from the excited state of the monomeric bacteriochlorophyll BA*.

scholarly journals Pump Probe Anisotropy Studies of the Photosynthetic Reaction Center

1999 ◽  
Vol 19 (1-4) ◽  
pp. 161-164
Author(s):  
D. C. Arnett ◽  
C. C. Moser ◽  
P. L. Dutton ◽  
N. F. Scherer
Keyword(s):  
Energy Transfer ◽  
Reaction Center ◽  
Charge Separation ◽  
Energy Levels ◽  
Photosynthetic Reaction Center ◽  
Ir Absorption ◽  
Optical Pulses ◽  
Pump Probe ◽  
Special Pair ◽  
Near Ir

The photosynthetic reaction center of Rb. sphaeroides is investigated by unique pump-probe anisotropy methods using 13 fs optical pulses tunable throughout the near IR absorption band. The time and wavelength resolved pump probe anisotropy transients yield detailed experimental descriptions of the energy levels, Py+ and Py- of the excitonically coupled special pair (P), and dynamics prior to charge separation, particularly energy transfer from the accessory bacteriochlorophylla's (B) to the special pair (P).

scholarly journals Excitonic structure and charge separation in the heliobacterial reaction center probed by multispectral multidimensional spectroscopy

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yin Song ◽  
Riley Sechrist ◽  
Hoang H. Nguyen ◽  
William Johnson ◽  
Darius Abramavicius ◽  
...  
Keyword(s):  
Reaction Center ◽  
Charge Separation ◽  
Electronic Spectroscopy ◽  
Spectroscopic Studies ◽  
Primary Electron ◽  
Reaction Centers ◽  
Separation Mechanism ◽  
Photosynthetic Reaction Centers ◽  
Density Analysis ◽  
Function Relationship

AbstractPhotochemical reaction centers are the engines that drive photosynthesis. The reaction center from heliobacteria (HbRC) has been proposed to most closely resemble the common ancestor of photosynthetic reaction centers, motivating a detailed understanding of its structure-function relationship. The recent elucidation of the HbRC crystal structure motivates advanced spectroscopic studies of its excitonic structure and charge separation mechanism. We perform multispectral two-dimensional electronic spectroscopy of the HbRC and corresponding numerical simulations, resolving the electronic structure and testing and refining recent excitonic models. Through extensive examination of the kinetic data by lifetime density analysis and global target analysis, we reveal that charge separation proceeds via a single pathway in which the distinct A0 chlorophyll a pigment is the primary electron acceptor. In addition, we find strong delocalization of the charge separation intermediate. Our findings have general implications for the understanding of photosynthetic charge separation mechanisms, and how they might be tuned to achieve different functional goals.

A Stepwise Electron-Transfer Relay Mimicking the Primary Charge Separation in Bacterial Photosynthetic Reaction Center

1996 ◽  
Vol 118 (1) ◽  
pp. 155-168 ◽  
Author(s):  
Atsuhiro Osuka ◽  
Shinji Marumo ◽  
Noboru Mataga ◽  
Seiji Taniguchi ◽  
Tadashi Okada ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Reaction Center ◽  
Charge Separation ◽  
Photosynthetic Reaction Center ◽  
Primary Charge Separation ◽  
Bacterial Photosynthetic Reaction Center

scholarly journals Excitonic Structure and Charge Separation in the Heliobacterial Reaction Center Probed by Multispectral Multidimensional Spectroscopy

2021 ◽  
Author(s):  
Yin Song ◽  
Riley Sechrist ◽  
Hoang Huy Nguyen ◽  
William Johnson ◽  
Darius Abramavičius ◽  
...  
Keyword(s):  
Reaction Center ◽  
Charge Separation ◽  
Electronic Spectroscopy ◽  
Spectroscopic Studies ◽  
Primary Electron ◽  
Reaction Centers ◽  
Separation Mechanism ◽  
Photosynthetic Reaction Centers ◽  
Density Analysis ◽  
Function Relationship

<p>Photochemical reaction centers are the engines that drive photosynthesis. The reaction center from heliobacteria (HbRC) has been proposed to most closely resemble the common ancestor of photosynthetic reaction centers, motivating a detailed understanding of its structure-function relationship. The recent elucidation of the HbRC crystal structure motivates advanced spectroscopic studies of its excitonic structure and charge separation mechanism. We perform multispectral two-dimensional electronic spectroscopy of the HbRC and corresponding numerical simulations, resolving the electronic structure and testing and refining recent excitonic models. Through extensive examination of the kinetic data by lifetime density analysis and global target analysis, we reveal that charge separation proceeds via a single pathway in which the distinct A<sub>0 </sub>chlorophyll <i>a</i> pigment is the primary electron acceptor. In addition, we find strong delocalization of the initial excited state and charge separation intermediate. Our findings have general implications for the understanding of photosynthetic charge separation mechanisms, and how they might be tuned to achieve different functional goals.</p>

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