Download or read book Exploiting Proton and Electron transfer Effects to Understand the Mechanism of Water Oxidation in Photosystem II written by Gözde Ulas and published by . This book was released on 2012 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Molecular Mechanisms of Proton coupled Electron Transfer and Water Oxidation in Photosystem II written by Shin Nakamura and published by . This book was released on 2020 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book reviews photosynthetic water oxidation and proton-coupled electron transfer in photosystem, focusing on the molecular vibrations of amino acid residues and water molecules. Photosynthetic water oxidation performed by plants and cyanobacteria is essential for the sustenance of life on Earth, not only as an electron source for synthesizing sugars from CO2, but also as an O2 source in the atmosphere. Water oxidation takes place at the Mn4CaO5cluster in photosystem II, where a series of electron transfer reactions coupled with proton transfer occur using light energy. The author addresses the unresolved mechanisms of photosynthetic water oxidation and relevant proton-coupled electron transfer reactions using a combined approach of experimental and computational methods such as Fourier transform infrared difference spectroscopy and quantum chemical calculations. The results show that protonation and hydrogen-bond structures of water molecules and amino acid residues in the protein play important roles in regulation of the electron and proton transfer reactions. These findings and the methodology make a significant contribution to our understanding the molecular mechanism of photosynthetic water oxidation.
Download or read book Photosynthetic Water Oxidation and Proton coupled Electron Transfer written by Ian Blake Cooper and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Photosystem II (PSII) is the membrane-bound oxidoreductase peptide complex responsible for the oxidation of water to molecular oxygen and reduction of plastoquinone to plastoquinol. Primary electron transfer is initiated upon absorption of a photon by the primary donor chl resulting in electron transfer and production of a P680+QA charge separated state. P680+ is reduced by YZ (Y161 of the D1 polypeptide subunit), one of two redox-active tyrosine residues found in PSII. This produces a neutral tyrosyl radical (YZ) which is subsequently reduced by electrons derived from water at the oxygen-evolving complex (OEC). The OEC is composed of four manganese, one calcium ion, and one chloride ion. Four photons are required to convert water to O2, each photon advancing the OEC through successive oxidation states or S states. The exact chemical mechanism of water oxidation in PSII is not known. However, proton-coupled electron transfer (PCET) is thought to be one of the fundamental steps in driving the extraction of electrons and protons from water. Here, the mechanism of water oxidation is investigated with focus on PCET events using vibrational spectroscopy. Vibrational spectroscopy is sensitive to changes in protein structure, charge, and hydrogen bonding, and is ideal for the study of fast events coupled with light-induced electron transfer. The results presented here demonstrate the utility of time-resolved infrared spectroscopy in the detection of intermediates of photosynthetic water oxidation. We suggest that proton transfer may precede manganese oxidation during water oxidation based on time-resolved infrared and difference FT-IR spectroscopic results. The mechanism of PCET associated with YZ reduction is investigated. Using reaction-induced difference FT-IR spectroscopy, the identity of the chloride binding site is speculated through the use of bromide exchange at the OEC. Also, proton transfer reactions at the OEC are investigated using azide as a vibrational probe. The advances in the understanding of photosynthetic water oxidation gained in this work will aid in the elucidation of the chemical mechanism of this important reaction. Understanding the details of photosynthetic water oxidation will assist in the development of technology aimed at harnessing the energy of the sun for the benefit of humankind.
Download or read book Chemical Complementation Studies of Proton coupled Electron Transfer Reactions in Photosystem II written by Anna-Maria Andrea Hays and published by . This book was released on 1999 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Spectroscopic Investigations of Photosynthetic Water Oxidation in Photosystem II written by Kelly Mark Halverson and published by . This book was released on 2002 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proton Transfer Reactions in Photosynthetic Water Oxidation written by Preston Lee Dilbeck and published by . This book was released on 2012 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scope and Method of Study: Physiological and Biophysical characterization of point mutations in the D1 subunit of PSII
Download or read book Photosystem II written by T. Wydrzynski and published by Springer Science & Business Media. This book was released on 2006-01-27 with total page 786 pages. Available in PDF, EPUB and Kindle. Book excerpt: The most mysterious part of photosynthesis yet the most important for all aerobic life on Earth (including ourselves) is how green plants, algae and cyanobacteria make atmospheric oxygen from water. This thermodynamically difficult process is only achieved in Nature by the unique pigment/protein complex known as Photosystem II, using sunlight to power the reaction. The present volume contains 34 comprehensive chapters authored by 75 scientific experts from around the world. It gives an up-to-date account on all what is currently known about the molecular biology, biochemistry, biophysics and physiology of Photosystem II. The book is divided into several parts detailing the protein constituents, functional sites, tertiary structure, molecular dynamics, and mechanisms of homeostasis. The book ends with a comparison of Photosystem II with other related enzymes and bio-mimetic systems. Since the unique water-splitting chemistry catalyzed by Photosystem II leads to the production of pure oxygen gas and has the potential for making hydrogen gas, a primary goal of this book is to provide a molecular guide to future protein engineers and bio-mimetic chemists in the development of biocatalysts for the generation of clean, renewable energy from sunlight and water.
Download or read book The Tuning of Electron and Proton coupled Electron Transfer Reactions of Solar Water Oxidation Pulsed Magnetic Resonance Spectroscopy Studies of Photosystem II written by Christopher S. Coates and published by . This book was released on 2013 with total page 784 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Redox Active Tyrosines in Photosystem II written by James M. Keough and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Proton coupled electron transfer reactions often involve tyrosine residues, because when oxidized, the phenolic side chain deprotonates. Tyrosine Z (YZ) is responsible for extracting electrons in a stepwise fashion from the oxygen evolving-complex in order to build enough potential to oxidize water. This process requires that each step YZ must deprotonate and reprotonate in order to maintain the high midpoint potential that is necessary to oxidize the oxygen-evolving complex, which makes YZ highly involved in proton coupled electron transfer reactions. In this thesis YZ has been studied within oxygen-evolving photosystem II utilizing electron paramagnetic resonance spectroscopy to monitor the tyrosyl radical that is formed upon light excitation. Kinetic analysis of YZ has shed light on the factors that are important for PSII to carry out water oxidation at the oxygen-evolving complex. Most notably the strong hydrogen-bonding network and the midpoint potential of YZ have been shown to be integral aspects of the water splitting reactions of PSII. By studying YZ within oxygen-evolving PSII, conclusions are readily applied to the native system.
Download or read book The Effects of SR2 substitution on the Reduction Rates of Y subscript Z nd on the Hydrogen Atom Abstraction Mechanism in Photosystem II written by Kristi Lee Westphal and published by . This book was released on 2000 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Oxygenic Photosynthesis The Light Reactions written by Donald R. Ort and published by Springer Science & Business Media. This book was released on 2006-04-11 with total page 681 pages. Available in PDF, EPUB and Kindle. Book excerpt: Structure and function of the components of the photosynthetic apparatus and the molecular biology of these components have become the dominant themes in advances in our understanding of the light reactions of oxygenic photosynthesis. Oxygenic Photosynthesis: The Light Reactions presents our current understanding of these reactions in thylakoid membranes. Topics covered include the photosystems, the cytochrome b6-f complex, plastocyanin, ferredoxin, FNR, light-harvesting complexes, and the coupling factor. Chapters are also devoted to the structure of thylakoid membranes, their lipid composition, and their biogenesis. Updates on the crystal structures of cytochrome f, ATP synthase and photosystem I are presented and a section on molecular biology and evolution of the photosynthetic apparatus is also included. The chapters in this book provide a comprehensive overview of photosynthetic reactions in eukaryotic thylakoids. The book is intended for a wide audience, including graduate students and researchers active in this field, as well as those individuals who have interests in plant biochemistry and molecular biology or plant physiology.
Download or read book Molecular Biology of The Cell written by Bruce Alberts and published by . This book was released on 2002 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Models for Electron Transfer in Photosystem II written by Demetrios F. Ghanotakis and published by . This book was released on 1984 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modeling the TyrZ His 190 Pair of Photosystem II for the Study of Proton Coupled Electron Transfer written by Dustin Patterson and published by . This book was released on 2011 with total page 83 pages. Available in PDF, EPUB and Kindle. Book excerpt: The work described in the thesis involves the synthesis of a molecular triad which is designed to undergo proton coupled electron transfer (PCET) upon irradiation with light. Photoinduced PCET is an important process that many organisms use and the elucidation of its mechanism will allow further understanding of this process and its potential applications. The target compound designed for PCET studies consists of a porphyrin chromophore (also a primary electron donor), covalently linked to a phenol-imidazole (secondary electron donor), and a C60 (primary electron acceptor). The phenol-imidazole moiety of this system is modeled after the TyrZ His-190 residues in the reaction center of Photosystem II (PS II). These residues participate in an intermolecular H-bond between the phenol side chain of TyrZ and the imidazole side chain of His-190. The phenol side chain of TyrZ is the electron transfer mediator between the oxygen evolving complex (OEC) and P680 (primary electron donor) in PSII. During electron transfer from TyrZ to P680*+, the phenolic proton of TyrZ becomes highly acidic (pKa~-2) and the hydrogen is preferentially transferred to the relatively basic imidazole of His-190 through a pre-existing hydrogen bond. This PCET process avoids a charged intermediate, on TyrZ, and results in a neutral phenolic radical (TyrZ*). The current research consists of building a molecular triad, which can mimic the photoinduced PCET process of PSII. The following, documents the synthetic progress in the synthesis of a molecular triad designed to investigate the mechanism of PCET as well as gain further insight on how this process can be applied in artificial photosynthetic devices.
Download or read book Chlorophyll a Fluorescence written by G.C. Papageorgiou and published by Springer Science & Business Media. This book was released on 2007-11-12 with total page 853 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chlorophyll a Fluorescence: A Signature of Photosynthesis highlights chlorophyll (Chl) a fluorescence as a convenient, non-invasive, highly sensitive, rapid and quantitative probe of oxygenic photosynthesis. Thirty-one chapters, authored by 58 international experts, provide a solid foundation of the basic theory, as well as of the application of the rich information contained in the Chl a fluorescence signal as it relates to photosynthesis and plant productivity. Although the primary photochemical reactions of photosynthesis are highly efficient, a small fraction of absorbed photons escapes as Chl fluorescence, and this fraction varies with metabolic state, providing a basis for monitoring quantitatively various processes of photosynthesis. The book explains the mechanisms with which plants defend themselves against environmental stresses (excessive light, extreme temperatures, drought, hyper-osmolarity, heavy metals and UV). It also includes discussion on fluorescence imaging of leaves and cells and the remote sensing of Chl fluorescence from terrestrial, airborne, and satellite bases. The book is intended for use by graduate students, beginning researchers and advanced undergraduates in the areas of integrative plant biology, cellular and molecular biology, plant biology, biochemistry, biophysics, plant physiology, global ecology and agriculture.
Download or read book Molecular Water Oxidation Catalysis written by Antoni Llobet and published by John Wiley & Sons. This book was released on 2014-04-14 with total page 343 pages. Available in PDF, EPUB and Kindle. Book excerpt: Photocatalytic water splitting is a promising strategy for capturing energy from the sun by coupling light harvesting and the oxidation of water, in order to create clean hydrogen fuel. Thus a deep knowledge of the water oxidation catalysis field is essential to be able to come up with useful energy conversion devices based on sunlight and water splitting. Molecular Water Oxidation Catalysis: A Key Topic for New Sustainable Energy Conversion Schemes presents a comprehensive and state-of-the-art overview of water oxidation catalysis in homogeneous phase, describing in detail the most important catalysts discovered today based on first and second row transition metals. A strong emphasis is placed on the description of their performance, as well as how they work from a mechanistic perspective. In addition, a theoretical description of some of the most relevant catalysts based on DFT are presented, as well as a description of related natural systems, such as the oxygen evolving system of photosystem II and the heme chlorite-dismutase. This book is a valuable resource for researchers working on water oxidation catalysis, solar energy conversion and artificial photosynthesis, as well as for chemists and materials scientists with a broad interest in new sustainable energy conversion schemes.
Download or read book Water in Biological and Chemical Processes written by Biman Bagchi and published by Cambridge University Press. This book was released on 2013-11-14 with total page 383 pages. Available in PDF, EPUB and Kindle. Book excerpt: A unified overview of the dynamical properties of water and its unique and diverse role in biological and chemical processes.
