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Direct Electrochemistry of Photosynthetic Proteins With University of Connecticut OpenCommons@UConn Doctoral Dissertations University of Connecticut Graduate School 11-24-2014 Direct Electrochemistry of Photosynthetic Proteins with Application to the Construction of a Photo- Bioelectrochemical Cell Yun Zhang University of Connecticut - Storrs, [email protected] Follow this and additional works at: https://opencommons.uconn.edu/dissertations Recommended Citation Zhang, Yun, "Direct Electrochemistry of Photosynthetic Proteins with Application to the Construction of a Photo-Bioelectrochemical Cell" (2014). Doctoral Dissertations. 602. https://opencommons.uconn.edu/dissertations/602 Direct Electrochemistry of Photosynthetic Proteins with Application to the Construction of a Photo-Bioelectrochemical Cell Yun Zhang, Ph.D. University of Connecticut, 2014 Direct voltammetry of the redox cofactors in bacterial reaction center (RC) proteins and spinach PSII core complex was investigated in this dissertation. Peak assignments were made through the use of comparisons with multiple control experiments involving isolated proteins, those depleted of specific cofactors and those affected by exogenous chemical reagents. RCs having undergone site-specific mutagenesis were examined by cyclic voltammetry (CV) and square wave voltammetry (SWV) methods. The heterogeneous electron transfer rate constants were extracted from the datasets and simulations were used to determine the number of electrons transferred between the cofactor and the electrode. The work seeks to provide a deeper understanding of the dynamic electrochemical processes undergone by redox active proteins. In addition, the PSII core complex provided the basis for a novel photo-biofuel cell. Chapter 2 describes direct voltammetry study of the electrochemical properties of bacterial RC in lipid dimyristoylphosphatidyl choline (DMPC) or as layer by layer (LbL) films with polyions. SWV of site-directed mutants RC films showed shifts in oxidation peak potential of primary electron donor that correlated reasonably with those reported from electrochemical titration experiment. Yun Zhang — University of Connecticut, 2014 Chapter 3 focuses on direct thin film voltammetry of spinach PSII complex also in lipid and polyion films. CV experiments were also carried out on isolated cytochrome b-559, Mn depleted PSII and purified Chl to help in the assignment of the peaks. These assignments were further supported by fitting the voltammetric data to appropriate simulation models which also provided heterogeneous electron transfer rate constants. Chapter 4 explores the kinetic properties of DMPC-WTRC films on a propyl-aminomethoxysilane (AS) modified slide and an indium tin oxide (ITO) slide. We compared results in films with those in RC solutions to check whether the fabricated films change the kinetic spectral properties. Chapter 5 reports the first application of spinach protein Photosystem II (PSII) core complex in lipid films in a photoelectrochemical device. PSII in DMPC film on a pyrolytic graphite (PG) worked as anode, and Pt black mesh cathode was used as cathode, which can produce voltage and power respectively higher than and comparable to a previous published report of a PSII photobiofuel cell. Direct Electrochemistry of Photosynthetic Proteins with Application to the Construction of a Photo-Bioelectrochemical Cell Yun Zhang B.S. Applied Chemistry (Fine Chemical Engineering), Dalian University of Technology, 2007 A Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree of Doctoral of Philosophy at the University of Connecticut 2014 Copyrighted by Yun Zhang 2014 APPROVAL PAGE Doctor of Philosophy Dissertation Direct Electrochemistry of Photosynthetic Proteins with Application to the Construction of a Photo-Bioelectrochemical Cell Presented by Yun Zhang, B.S. Major Advisor James F. Rusling Associate Advisor Harry A. Frank Associate Advisor Challa V. Kumar University of Connecticut 2014 ii Dedicated to My Parents Bing and Ziying 2014 iii ACKNOWLEDGEMENTS I would like to thank my academic advisor, Prof. James F. Rusling who give me guidance, patience, encouragement and support throughout my Ph.D. training and research. Thanks very much Jim, you set up a good example for me. I also would like to thank to Prof. Harry A. Frank, my associate advisor and our collaborator on photosynthetic reaction center project. I greatly appreciate your guidance, valuable suggestions, discussions and support throughout this hard project. Many thanks go to other members of my advisory committee, Prof. Challa V. Kumar I learned a lot from your constant support, training and inspirations. Thanks to Dr. Linlin Zhao for as my mentor to train me all basic electrochemistry methods, encouraging me to do independent research. Many thanks to Dr. Frank’s research group members, Nikki Magdaong, Dr. Mia Enriquez, Amy LaFountain, Dr. Marcel Fuciman for the preparation of photosynthetic reaction centers and help me understanding the structure and function of these proteins. Thanks to Dr. Rusling’s group members: Dr. Linlin Zhao, Dr. Shenmin Pan, Dr. Hongyun Liu, Dr. Sadagopan Krishnan, Dandan Li, Colleen Krause, Boya Song, for your friendship and support. My deepest thanks to my parents, friends: Kun Fang, Ying Wang and Danjie Zhang, for your encouragement, understanding, support for the course of the work. iv TABLE OF CONTENTS APPROVAL PAGE ........................................................................................................... ii ACKNOWLEDGEMENTS ............................................................................................ iv TABLE OF CONTENTS .................................................................................................. v LIST OF SCHEMES ........................................................................................................ x LIST OF FIGURES ......................................................................................................... xi LIST OF TABLES .......................................................................................................... xix CHAPTER 1 Introduction ......................................................................................... 1 1.1 Goals and Significance ......................................................................................... 1 1.2 Photosynthetic Reaction Center ........................................................................... 3 1.2.1 Bacterial Reaction center .............................................................................. 3 1.2.2 PSII ............................................................................................................... 5 1.3 Protein film votammetry ...................................................................................... 6 1.3.1 Film fabrication methods for PFV ................................................................ 7 1.3.2 Electrochemistcal methods ........................................................................... 8 1.4 Previous studies direct voltammetry of bacterial RCs and PSII ........................ 10 1.5 Applications of photosynthetic proteins in photobioelectrochemical devices ... 11 1.6 References .......................................................................................................... 13 v CHAPTER 2 Thin Film Voltammetry of Wild Type and Mutant Reaction Center Proteins from Photosynthetic Bacteria ......................................................................... 18 2.1 Abstract .............................................................................................................. 18 2.2 Introduction ........................................................................................................ 18 2.3 Experimental Section ......................................................................................... 22 2.3.1 Materials. .................................................................................................... 22 2.3.2 Electrode and film preparation. ................................................................... 23 2.3.3 Voltammetry ................................................................................................ 24 2.3.4 Spectroscopy ............................................................................................... 24 2.4 Results ................................................................................................................ 24 2.4.1 Film construction and characterization. ...................................................... 25 2.4.2 Thin Film Voltammetry. .............................................................................. 27 2.4.3 Comparison of WTRC and mutant RCs. .................................................... 33 2.5 Discussion .......................................................................................................... 34 2.6 Conclusion .......................................................................................................... 38 2.7 References .......................................................................................................... 39 CHAPTER 3 Protein Film Voltammetry and Co-factor Electron Transfer Dynamics in Spinach Photosystem II Core Complex .................................................. 43 3.1 Abstract .............................................................................................................. 43 3.2 Introduction .......................................................................................................
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