Mechanisms of charge separation and protein relaxation processes in native and modified reaction centers of photosynthetic bacteria Rb. sphaeroides R26 studied by picosecond time resolved fluorescence [Elektronische Ressource] / Pancho Tzankov

Tzankov

Informations

• Publié par: technische_universitat_munchen
• Publié le: 01 janvier 2003
• Nombre de lectures: 18
• Langue: English
• Poids de l'ouvrage: 2 Mo

Extrait

Institut für Physikalische und Theoretische Chemie
der Technischen Universität München




Mechanisms of Charge Separation and Protein Relaxation
Processes in Native and Modified Reaction Centers of
Photosynthetic Bacteria Rb. sphaeroides R26 Studied by
Picosecond Time Resolved Fluorescence.





Pancho Tzankov





Vollständiger Abdruck der von der Fakultät für Chemie der Technischen Universität
München zur Erlangung des akademischen Grades eines




Doktors der Naturwissenschaften




genehmigten Dissertation.




Vorsitzender: Univ.-Prof. Dr. H. J. Neusser
Prüfer der Dissertation:
1. Priv.-Doz. Dr. A. Ogrodnik
2. Univ.-Prof. Dr. H. Scheer,
Ludwig-Maximilians-Universität München





Die Dissertation wurde am 01.07.2003 bei der Technischen Universität München
eingereicht und durch die Fakultät für Chemie am 11.09.2003 angenommen.





































In memory of Nickolay Panchev Tzankov, my Father. TABLE OF CONTENTS


Table of Contents

1. Introduction…………………………………….…………………………………………….1

2. Experimental methods…………………………………………………………………….…4
2.1. Picosecond time-resolved fluorescence measurements………………………….………..4
2.2. Time-correlated single photon counting…………………………………………………..4
2.3. The numerical analysis of the measurements…………………………………….……….6

3. Theoretical background of the photoinduced electron transfer………………..…………8
3.1. Introduction………………………………………………………………………………..8
3.2. Electron transfer rates…………………………………………………………………..10
3.3. Nonadiabatic electron transfer………………………………………………….……......12
3.4. Adiabatic vs. nonadiabatic electron transfer…………………...…………….……...…...13
3.5. Adiabatic vs. nonadiabatic electron transfer……………………………………………..13
3.6. Quantum-mechanical nonadiabatic limit – nuclear tunneling………….…….……….....16
3.7. Classical nonadiabatic limit – Marcus theory………………………………………....…17
3.8. Frank-Condon factor in multi-mode approximation……………………………...……...18
3.9. Superexchange mediated electron transfer………………………………………..……...21

+4. Temperature dependence of the conformational relaxation of the state P H ¯ in R26 A
reaction centers of Rb. sphaeroides………………………………………………...………....23
4.1. Introduction……………………………………………………………………………....23
1 * 4.2. Method of discriminating between "prompt" emission of P and "delayed" emission
+reflecting equilibrium with P H ¯………………………………………………………………24 A
1 * + 4.3. Method for obtaining the free energy separation between P and P H ¯ in case of A
inhomogeneously broadened radical pair state……………………………………...…………..26
1 * + 4.4. Obtaining the time dependence of the free energy separation between P and P H ¯….28 A
4.5. Time-resolved temperature dependent fluorescence data……………………...………...32
+ 4.6. Temperature and time dependent P H ¯ free energy relaxation data……………………39 A
+ 4.7. Discussion of the P H ¯ relaxation in terms of the existing theories and empirical A
approaches………………………………………………………………………………………47
4.8. Conclusions………………………………………………………………………………60

5. Sequential vs. superexchange charge separation in Vinyl-B -R26 reaction centers of Rb. AB
sphaeroides……………………………………………………………..………………………61
i TABLE OF CONTENTS


4.1. Introduction…………………………………………………………………………...….61
5.2. Vinyl reaction centers preparation…………………..…………………………………...62
5.3. Control of reaction centers modification….……………………………………………...63
5.4. Temperature dependence of the primary donor lifetime in Vinyl reaction centers……....64
5.5. Kinetic model……………………………………………………………..…………..….71
+ 5.6. Kinetic model including temperature dependence of the depopulation rate of P B ¯…...75 A
+ 5.7. Kinetic model considering the inhomogeneous distribution of P B ¯ radical pair free A
energies………………………………………………………………………………………....78
5.8. Superexchange enhanced electron transfer below 200 K………………………………..80
5.9. Conclusion……………………………………………………………..….……………..81

6. Time-resolved electric field effects on the fluorescence of Vinyl-B -R26 reaction centers AB
of Rb. sphaeroides………………………………………………………………………......….82
4.1. Introduction………………………………………………………………………….…...82
6.2. How does an electric field influence electron transfer?………………………………..…84
6.3. The TREFIFA method…………………………………………………………...……....86
6.4. Experimental features and results…………………………………………...……...…....91
6.5. Time-dependent orientation of the transition moment of the primary charge separation..96
+ 6