The 2010-1st International OCARINA Symposium
OCU Media Center 10F
December 8th, 2010

The OCU Advanced Research Institutefor Natural Science and Technology
http://www.ocarina-ocu.jp/

The 2010-1st- International OCARINA Symposium
Venue: OCU Media Center 10F, December 8th, 2010

Program
13:00-13:05

Opening Remark

13:05-13:50“Solar to Fuels; Natural Tactics of Solar Energy Conversion byPhotosynthesis”
Hideki Hashimoto (OCARINA A-group Leader)

13:55-14:15“Organo-copper complex as an interface for photosynthetic system”
Isamu Kinoshita (OCARINA A-group)

14:20-14:40“Key Residues and their Protonation States in the Reaction Pathwayof TtADPRase”
Yoshihiko Furuike (OCARINA A-group)

14:45-15:05“Atomic Force Microscopy Observation of Reconstituted
Photosynthetic Membranes”
Yuko Sugai (OCARINA A-Group)

15:05-15:30

Break

15:30-16:30“EXCITED STATE LEVEL STRUCTURE AND ULTRAFAST
RELAXATION DYNAMICS IN CAROTENOIDS”
Alfred R. Holzwarth (Max-Planck-Institut für BioanorganischeChemie, Germany)

16:30-17:30“Contrasting One-Photon and Two-Photon Initiated Dynamics ofCarotenoids in Solution and Light Harvesting Proteins”
Delmar S. Larsen (Department of Chemistry, University ofCalifornia Davis, USA)

Informal banquet will be opened at AOGAKI

3

Solar to Fuels; Natural Tactics of Solar Energy Conversion
by Photosynthesis
Hideki Hashimoto
CREST-JST and The OCU Advanced Research Institute for Natural Scienceand Technology (OCARINA), Osaka City University, Sugimoto,Sumiyoshi-ku, Osaka 558-8585, Japan

70% of mankind’s current energy needs are met by burning fossil fuels. This is alreadyproblematic since oil and gas supplies are limited and because of the adverse environmental
effects of rising levels of carbon dioxide in the atmosphere. Moreover this situation is set to getworse as current predictions estimate that our energy needs will double by 2050. Mankind is,therefore, facing a major challenge to find new ways of creating clean, renewable fuels. One
potentially abundant source of energy is solar radiation. More energy strikes the earth surface
every hour than mankind uses each year. The problem is how to harness such an abundant yet
diffuse source of energy. Photosynthesis has evolved mechanisms to achieve this. Conceptually
photosynthesis can be divided into the following partial reactions, light-harvesting(concentration), charge-separation (conversion of solar energy into chemical energy) and finallymulti-electron catalysis that takes electrons from water and uses them to reduce carbon dioxide tocarbohydrates (fuel).
Any proposed strategies that set out to mimic this process in order to make solar fuels must
begin with a light-harvesting or light-concentration step. We know a great deal about the structureand function of photosynthetic light-harvesting complexes as individual molecules, but rather
little is known about how their supra-molecular organization within their photosynthetic
membranes affects their overall function in vivo. We wish to understand how the supra-moleculararrangement of the light-harvesting apparatus relates to overall light-harvesting efficiency and to
be able to translate this information to inform the design of robust artificial light-harvestingarrays that can, in the long term, be used in devices for producing solar fuels. Photosynthetic
antenna complexes are organised on the nanoscale (see Figure 1) and a major question is how totranslate this information into the design of meso- to macroscale light-harvesting devices.
This lecture will outline how photosynthesis achieves ‘Solar to Fuels’ conversion
concentrating on the general principles involved. Recent progress on understating the moleculardetails of the key reactions in the photosynthetic process has been remarkable. We are now at thestage where it is realistic to start to use this ‘biological blueprint’ to begin to construct devices
that have the capability to mimic the key steps in the natural process. This is one of the grandscientific challenges of our time.

Figure 1. A cartoon of the purple bacterial
photosynthetic unit (PSU) with the times of themajor Bchl → Bchl energy transfer reactions
indicated. This is a hypothetical model of the PSU
designed to help the reader visualised the various
energy transfer steps that have been time-resolved.
It is not meant to represent how these complexes
are organised relative to each other in the natural
photosynthetic membrane.

Atomic Force Microscopy Observation of Reconstituted
Photosynthetic Membranes
Yuko Sugai1, Ayumi Sumino2,3, Chiasa Uragami1, Ritsuko Fujii1,4,Takanori Nishioka1, Takehisa Dewa2, Isamu Kinoshita1,4, Mamoru
Nango1, Hideki Hashimoto1,41
CREST/JST and Graduate School of Science, Osaka City University,Osaka, Japan, 2Department of Life and Materials Engineering, Nagoya
Institute of Technology, Nagoya, Japan, 3Institute of Advanced Energy,Kyoto University, Kyoto, Japan, 4The OCU Advanced ResearchInstitute for Natural Science and Technology (OCARINA), Osaka City
University, Osaka, Japan,
The primary process of photosynthesis involves the absorption of sun-light by antennacomplexes and subsequent transfer of excitation energy towards the reaction center where acharge separation takes place. This process is usually performed in a photosynthetic
membrane. Photosynthetic apparatus that contains the reaction centre (RC) and two types ofantenna complexes (the core antenna light-harvesting 1 (LH1) and the peripheral antennalight–harvesting 2 (LH2) complexes) are embedded in this membrane. RC is surrounded byLH1 to form LH1-RC core complex. The pattern how these light-harvesting pigment-protein
complexes are arranged in photosynthetic membrane may do have strong correlation with thelight-harvesting functions in the primary process of photosynthesis.
In this study, we have constructed artificial photosynthetic membranes in which theLH1-RC core complexes (from a purple photosynthetic bacterium, Blc. viridis) are installed.
Hybrid photosynthetic membranes were also fabricated by introducing both the LH2 (fromRps. acidophila) and LH1-RC core complexes (from Blc. viridis) to a lipid bilayer systemcomposed of Egg PC. The architecture of the artificial photosynthetic membrane can bevaried by controlling the ratio of added LH2 to LH1-RC core complexes (LH1-RC/LH2 = 1/1,1/2, 1/5, 1/12). Previous study using transmission electron microscopy (TEM) showed thatthe packing of LH1-RC with the trigonal lattice was changed to orthorhombic as increasing
the ratio of LH2 [1].
In order to investigate the more detailed arrangement of pigment-protein complexes,
atomic force microscopy (AFM) observation was performed for the similar artificial
photosynthetic membranes. Membranes were adsorbed on a fleshly cleaved mica surface andwere observed by AFM with
non-contact mode under ambienta)b)condition. Fig. 1 shows the hybrid
reconstituted photosynthetic membraneof LH1-RC/LH2 = 1/2. LH1-RC andLH2 can be easily discriminatedbecause of the different height andparticle size of these complexes interms of the AFM topography.
Furthermore, high resolution AFM Fig. 1 AFM topography (a) and line profile of whiteline (b) of hybrid reconstituted photosynthetic
images revealed the lattice arrangement membrane of LH1-RC/LH2 = 1/2 under ambientof LH1-RC core complexes.
condition.
The present study is quite importantfor understanding the detailed relationship between the arrangement of photosynthetic
pigment–protein complexes and the energy transfer among them.
[1] R. Fujii et al., Photosynth. Res. 2008, 95, 327

EXCITED STATE LEVEL STRUCTURE ANDULTRAFAST RELAXATION DYNAMICS IN
CAROTENOIDS
Alfred R. Holzwarth
Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36,
45470 Mülheim a.d. Ruhr, Germany,e-mail: holzwarth@mpi-muelheim.mpg.deThere exists general agreement about the location and dynamics of two excited states in“normal” carotenoids not possessing charge transfer states. These are the low-lying firstexcited 2Ag- state, which is a dark state relative to the ground state, and the 1Bu+ state(generally called the S2 state) which gives the colour to carotenoids due to its very strongtransition moment from the ground state (for a review see 1). However a long-standing debate
has been taking place in the literature about the nature and energetic location of additional socalled “dark states” between the S1 and the S2 states. The most prominent one that also has agood theoretical foundation is the 1Bu- state, generally considered to be a “dark state”, i.e. notcarrying oscillator strength from the ground state. We have shown recently that in carotenoidsof conjugation length n=10-11 the 1Bu- state actually is located slightly below the 1Bu+ state
and that the two potential curves cross each other, giving rise to electronic coherence udner
certain conditions2. Besides some vibrationally unrelaxed S2 states, some publications
reported additional states with fairly unusual spectroscopic properties which were proposed to
be located between the S1 and the S2 states (4-6). These states were termed e.g. Sx, S* etc. andtheir molecular and electronic assignment is at best highly controversial if not totally unclear.
For example, we recently showed that the so-called S* state in β-carotene is not a separate
electronic state but a vibrationally excited (hot) 2Ag- state3.
In this talk an effort will be made to sort out some of the controversies and confusion
about this “zoo” of excited states in “normal” (i.e. ignoring those situations where CT states
are involved) longer chain carotenoids of conjugation length n=9-13. A new electronic level
scheme will be proposed explaining the puzzles of the ultrafast relaxation of the S2 state andthe related electronic coherences.
References
1. Polivka, T.; Sundström, V. Dark excited states of carotenoids: Consensus andcontroversy. Chem. Phys. Lett. 2009, 477 (1-3), 1-11.
2. Ostroumov, E.; Müller, M. G.; Marian, C. M.; Kleinschmidt, M.; Holzwarth, A. R.
Electronic coherence provides a direct proof for energy-level crossing inphotoexcited lutein and β-carotene. Phys. Rev. Lett. 2009, 103, 108302-1108302-4.
3. Ostroumov, E. E.; Müller, M.; Reus, M.; Holzwarth, A. R. On the nature of the "darkS*" excited state of β-carotene. J. Phys. Chem. B 2010, in print.

Contrasting One-Photon and Two-Photon
Initiated Dynamics of Carotenoids in Solution
and Light Harvesting Proteins
Delmar S. Larsen
Department of Chemistry, University of California, Davis
One Shields Avenue Davis, CA 95616 USA

Although observed in multiple carotenoid samples, the exact nature of the S* state isstill debated, including the electronic structure and ensuring formation and decay
dynamics. Consequently, several models have been proposed regarding the ultrafastexcited state kinetics in carotenoids; unfortunately, many studies are hindered by theinability to cleanly resolve the S* state from the overlapping S1 excited state absorption
and bleach contributions to the transient signals. This is further compounded by thesimilarity in S* lifetime to S1. We explore the nature of S* with femtosecond
one-photon and two-photon initiated dynamics of the all trans β-carotene carotenoid,
which is further characterized and dissected with excitation-wavelength andtemperature-dependent ultrafast dispersed transient absorption signals. The S*population kinetics prompted the development of a modified multi-compartment model.
The interconnectivity of the S* and S1 populations is explored and discussed and noobserved population flow is resolved between S* and S1. Comparison of samples
obtained from different laboratories with different purity levels demonstrates thatsample contamination is not the primary origin of the S* state. Comparisons to thedynamics in the rhodopsin glucoside carotenoid bound to Rps. Acidophila will be made.