Photo-protective function of carotenoids in photosynthesis [Elektronische Ressource] / von Sergiu Amarie

Photo-protective Function of Carotenoids
in Photosynthesis






DISSERTATION
zur Erlangung des Doktorgrades
der Naturwissenschaften






vorgelegt beim Fachbereich
Biochemie, Chemie und Pharmazie
der Johann Wolfgang Goethe-Universität
in Frankfurt am Main












von
Sergiu Amarie
aus Dorohoi





Frankfurt am Main, 2008





vom Fachbereich Biochemie, Chemie und Pharmazie der
Johann Wolfgang Goethe-Universität als Dissertation angenommen.































Dekan: Prof. Dr. Dieter Steinhilber
1. Gutachter: Prof. Dr. Josef Wachtveitl
2. Gutachter: PD Dr. Andreas Dreuw

Datum der Disputation: 17.03.2009



Contents
1 Introduction.......................................................................................................................... 1
1.1 Photosynthesis.................................................................................................................2
1.2 Non-photochemical Quenching ......................................................................................3
1.3 Pigments..........................................................................................................................5
1 1.3.1 (Bacterio)Chlorophylls........................................................................................5
2 1.3.2 Carotenoids..........................................................................................................8
1.4 Plant Light-Harvesting Complexes...............................................................................12
3 1.4.1 Light-Harvesting Complex II (LHC II) ............................................................. 13
4 1.4.2 Minor Peripheral Antenna Complexes (CP24, CP26 and CP29) ...................... 16
1.5 Bacterial Light Harvesting Complex 1 (LH1) ..............................................................17

2 Experimental Methods ...................................................................................................... 19
2.1 The Femtosecond Laser System ...................................................................................20
5 2.1.1 Non-collinear Optical Parametric Amplifier (NOPA)....................................... 21
6 2.1.2 Pulse Compressor .............................................................................................. 22
7 2.1.3 White Light Generation..................................................................................... 23
8 2.1.4 Detector and Choppers ...................................................................................... 23
2.2 General Description of the Pump-probe Method..........................................................25
2.3 Data Analysis................................................................................................................27

3 Excited State Dynamics of Rhodospirillium rubrum Reaction Center Mutants........... 28
3.1 Introduction...................................................................................................................28
3.2 Materials and Methods..................................................................................................31
3.3 Results...........................................................................................................................32
9 3.3.1 Steady-state Absorption Spectroscopy .............................................................. 32
10 3.3.2 Excited State Dynamics of Wild Type, SPUHK1 and SK ∆LM Mutants of
Rhodospirillium rubrum PSU Following Excitation of the Spx S State................... 33 2
3 311 3.3.3 Photoprotection via Triplet Energy Transfer from BChl to Car ..................... 39
3.4 Discussion.....................................................................................................................43

4 Carotenoid Radical Cation as a Probe for Non-photochemical Quenching................. 45
4.1 Introduction...................................................................................................................45
4.2 Sample Preparation .......................................................................................................47
4.3 Chlorophyll Excited-State Dynamics in LHC Proteins ................................................48
12 4.3.1 Excitation Energy Transfer................................................................................ 48
13 4.3.2 Electron Transfer ............................................................................................... 51
4.4 Generation of Carotenoid Radical Cations in Solution.................................................53
4.5 Carotenoid Radical Cation Detection in LHC II...........................................................58
4.6 Discussion.....................................................................................................................60
14 4.6.1 Location and Mechanism of qE......................................................................... 62

5 Carotenoid Radical Cation Proprieties............................................................................ 64
IV
5.1 Introduction.................................................................................................................. 64
5.2 Materials and Methods................................................................................................. 66
5.3 Results and Discussion ................................................................................................ 67
15 5.3.1 Optical Properties of Lutein and β-Carotene Radical Cations .......................... 67
16 5.3.2 Excited State Dynamics of Carotenoid Radical Cations ................................... 69
17 5.3.3 Nature of the Low Lying Excited States of Carotenoid Radical Cations.......... 73
18 5.3.4 Chlorophyll Exited State Quenching by Carotenoid Radical Cations -
Implications for NPQ.................................................................................................. 75

6 Excited State Dynamics of Astaxanthin Radical Cation ................................................ 79
6.1 Introduction.................................................................................................................. 79
6.2 Materials and Methods................................................................................................. 81
6.3 Results.......................................................................................................................... 82
19 6.3.1 Excited State Dynamics of Astaxanthin in Chloroform .................................... 82
20 6.3.2 Optical Properties of the Astaxanthin Radical Cation....................................... 85
21 6.3.3 Excited State Dynamics of the Astaxanthin Radical Cation ............................. 87
6.4 Discussion.................................................................................................................... 91

7 Summary and Outlook ...................................................................................................... 94

References............................................................................................................................ 100

Acknowledgements ...................................................................................................................
Publications ...............................................................................................................................
Curriculum Vitae......................................................................................................................



V
List of Figures
1.1. Detailed model of the protein complexes involved in electron and proton transport
within the thylakoid membrane of green plants 2
1.2. Light conditions of field plants during one representative day 3
1.3. Possible fates of excited Chl embedded in the light harvesting complexes of plants 4
1.4. Structure of BChl a (left), Chl a and Chl b (right). R represents the phytyl
chain, R : CH for Chl a and CHO for Chl b. The arrow indicates the direction of the Q 1 3 y
transition dipole moment 6
1.5. Absorption spectra of chlorophyll a and b solubilized in methanol 6
1.6. Molecular structures of plant photosystem carotenoids, conjugation length is denoted
in parentheses .8
1.7. Room temperature absorption spectra of the neutral form of violaxanthin,
lutein, zeaxanthin and β-carotene 9
1.8. Transient absorption spectra of spinach thylakoids recorded upon excitation at
664 nm and probed at 1000 nm (left). Reconstructed quenched minus unquenched
difference spectrum (solid line with circles) at a time delay of 20 ps, together with the
•+spectrum of β-Car (dashed line) (right) 11
•+1.9. Scheme of the qE quenching mechanism, showing generation