400
T. Dewa et al.
kinetics. This comes from heterogeneous conditions of fluorophore in or around
protein environments. The LH2-NC-A647 demonstrated the single-phase dynamics
of sequential energy transfer in the micellar and lipid bilayer systems. Such simple
kinetics is quite rare as per our knowledge.
23.5 Conclusion
We described ultrafast excitation energy transfer in the biohybrid LH2s to which artificial chromophores A647 were covalently attached. We found that A647 successfully
functions as the external light-harvesting chromophore. The rates of energy transfer
were comparable to that takes place in natural systems. For the attachment of A647
to B800- and B850-sides, energy transfer exhibited multiexponential dynamics due
to heterogeneity of the environment around A647. In sharp contrast, engineered LH2
bearing the Cys residue on the B800 side exhibited simple monoexponential kinetics
of the sequential energy transfer A647 → B800 → B850.
LH2 conjugated with artificial pigments, therefore, will produce a promising motif
in the methodology to construct multichromophore devices. This will provide deeper
understanding of highly efficient energy transfer processes in natural photosynthetic systems, and clues for construction of highly efficient artificial photosynthetic
systems.
Acknowledgements T. D. deeply appreciates to Dr. Tomoyasu Noji and graduate students (Mr.
Daisuke Komori, Naoto Mizutani, Daiki Mori, and Ms. Akari Goto) for their contribution to
this project. The present work was supported by JSPS KAKENHI Grant Numbers JP26107002,
JP16J00627, and 17H05255, Grant-in-Aid for Scientific Research on Innovative Areas “Photosynergetics” and also by JP18H05160 and JP18H05180 in “Innovations for Light-Energy
Conversion.”
References
1. Inoue H, Shimada T, Kou Y, Nabetani Y, Masui D, Takagi S, Tachibana H (2011) The water
oxidation bottleneck in artificial photosynthesis: how can we get through it? An alternative
route involving a two-electron process. ChemSusChem 4:173–179
2. Scholes GD, Fleming GR, Olaya-Castro A, Van Grondelle R (2011) Lessons from nature about
solar light harvesting. Nat Chem 3:763–774
3. Green BR, Parson WW eds (2003) In: Light-harvesting antennas in photosynthesis. Kluwer
Academic publishers
4. Cogdell RJ, Lindsay JG (2000) The structure of photosynthetic complexes in bacteria and
plants: an illustration of the importance of protein structure to the future development of plant
science. New Phytol 145:167–196
5. Blankenship RE (2014) In: Molecular mechanisms of photosynthesis. Wiley Blackwell, UK
6. McDermott G, Prince SM, Freer AA, Hawthornthwaite-Lawless AM, Papiz MZ, Cogdell RJ,
Isaacs NW (1995) Crystal structure of an integral membrane light-harvesting complex from
photosynthetic bacteria. Nature 374:517–521
T. Dewa et al.
kinetics. This comes from heterogeneous conditions of fluorophore in or around
protein environments. The LH2-NC-A647 demonstrated the single-phase dynamics
of sequential energy transfer in the micellar and lipid bilayer systems. Such simple
kinetics is quite rare as per our knowledge.
23.5 Conclusion
We described ultrafast excitation energy transfer in the biohybrid LH2s to which artificial chromophores A647 were covalently attached. We found that A647 successfully
functions as the external light-harvesting chromophore. The rates of energy transfer
were comparable to that takes place in natural systems. For the attachment of A647
to B800- and B850-sides, energy transfer exhibited multiexponential dynamics due
to heterogeneity of the environment around A647. In sharp contrast, engineered LH2
bearing the Cys residue on the B800 side exhibited simple monoexponential kinetics
of the sequential energy transfer A647 → B800 → B850.
LH2 conjugated with artificial pigments, therefore, will produce a promising motif
in the methodology to construct multichromophore devices. This will provide deeper
understanding of highly efficient energy transfer processes in natural photosynthetic systems, and clues for construction of highly efficient artificial photosynthetic
systems.
Acknowledgements T. D. deeply appreciates to Dr. Tomoyasu Noji and graduate students (Mr.
Daisuke Komori, Naoto Mizutani, Daiki Mori, and Ms. Akari Goto) for their contribution to
this project. The present work was supported by JSPS KAKENHI Grant Numbers JP26107002,
JP16J00627, and 17H05255, Grant-in-Aid for Scientific Research on Innovative Areas “Photosynergetics” and also by JP18H05160 and JP18H05180 in “Innovations for Light-Energy
Conversion.”
References
1. Inoue H, Shimada T, Kou Y, Nabetani Y, Masui D, Takagi S, Tachibana H (2011) The water
oxidation bottleneck in artificial photosynthesis: how can we get through it? An alternative
route involving a two-electron process. ChemSusChem 4:173–179
2. Scholes GD, Fleming GR, Olaya-Castro A, Van Grondelle R (2011) Lessons from nature about
solar light harvesting. Nat Chem 3:763–774
3. Green BR, Parson WW eds (2003) In: Light-harvesting antennas in photosynthesis. Kluwer
Academic publishers
4. Cogdell RJ, Lindsay JG (2000) The structure of photosynthetic complexes in bacteria and
plants: an illustration of the importance of protein structure to the future development of plant
science. New Phytol 145:167–196
5. Blankenship RE (2014) In: Molecular mechanisms of photosynthesis. Wiley Blackwell, UK
6. McDermott G, Prince SM, Freer AA, Hawthornthwaite-Lawless AM, Papiz MZ, Cogdell RJ,
Isaacs NW (1995) Crystal structure of an integral membrane light-harvesting complex from
photosynthetic bacteria. Nature 374:517–521