Evaluating the Nature of So-called S*-State Feature in Transient Absorption of Carotenoids in Light-harvesting Complex 2 (LH2) from Purple Photosynthetic Bacteria PDF Download
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Languages : en
Pages : 9
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Book Description
Carotenoids are a class of natural pigments present in all phototrophic organisms, mainly in their light-harvesting proteins in which they play roles of accessory light absorbers and photoprotectors. Extensive time-resolved spectroscopic studies of these pigments have revealed unexpectedly complex photophysical properties, particularly for carotenoids in light-harvesting LH2 complexes from purple bacteria. An ambiguous, optically forbidden electronic excited state designated as S* has been postulated to be involved in carotenoid excitation relaxation and in an alternative carotenoid-to-bacteriochlorophyll energy transfer pathway, as well as being a precursor of the carotenoid triplet state. However, no definitive and satisfactory origin of the carotenoid S* state in these complexes has been established, despite a wide-ranging series of studies. Here, we resolve the ambiguous origin of the carotenoid S* state in LH2 complex from Rba. sphaeroides by showing that the S* feature can be seen as a combination of ground state absorption bleaching of the carotenoid pool converted to cations and the Stark spectrum of neighbor neutral carotenoids, induced by temporal electric field brought by the carotenoid cation- bacteriochlorophyll anion pair. Lastly, these findings remove the need to assign an S* state, and thereby significantly simplify the photochemistry of carotenoids in these photosynthetic antenna complexes.
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Category :
Languages : en
Pages : 9
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Book Description
Carotenoids are a class of natural pigments present in all phototrophic organisms, mainly in their light-harvesting proteins in which they play roles of accessory light absorbers and photoprotectors. Extensive time-resolved spectroscopic studies of these pigments have revealed unexpectedly complex photophysical properties, particularly for carotenoids in light-harvesting LH2 complexes from purple bacteria. An ambiguous, optically forbidden electronic excited state designated as S* has been postulated to be involved in carotenoid excitation relaxation and in an alternative carotenoid-to-bacteriochlorophyll energy transfer pathway, as well as being a precursor of the carotenoid triplet state. However, no definitive and satisfactory origin of the carotenoid S* state in these complexes has been established, despite a wide-ranging series of studies. Here, we resolve the ambiguous origin of the carotenoid S* state in LH2 complex from Rba. sphaeroides by showing that the S* feature can be seen as a combination of ground state absorption bleaching of the carotenoid pool converted to cations and the Stark spectrum of neighbor neutral carotenoids, induced by temporal electric field brought by the carotenoid cation- bacteriochlorophyll anion pair. Lastly, these findings remove the need to assign an S* state, and thereby significantly simplify the photochemistry of carotenoids in these photosynthetic antenna complexes.
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Category :
Languages : en
Pages : 468
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Book Description
Author: C.N. Hunter
Publisher: Springer Science & Business Media
ISBN: 1402088159
Category : Science
Languages : en
Pages : 1013
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Book Description
Here is a comprehensive survey of all aspects of these fascinating bacteria, metabolically the most versatile organisms on Earth. It compiles 48 chapters written by leading experts, who highlight the huge progress made in studies of these bacteria since 1995.
Author: Roberta Croce
Publisher: CRC Press
ISBN: 1351242873
Category : Science
Languages : en
Pages : 793
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Book Description
This landmark collective work introduces the physical, chemical, and biological principles underlying photosynthesis: light absorption, excitation energy transfer, and charge separation. It begins with an introduction to properties of various pigments, and the pigment proteins in plant, algae, and bacterial systems. It addresses the underlying physics of light harvesting and key spectroscopic methods, including data analysis. It discusses assembly of the natural system, its energy transfer properties, and regulatory mechanisms. It also addresses light-harvesting in artificial systems and the impact of photosynthesis on our environment. The chapter authors are amongst the field’s world recognized experts. Chapters are divided into five main parts, the first focused on pigments, their properties and biosynthesis, and the second section looking at photosynthetic proteins, including light harvesting in higher plants, algae, cyanobacteria, and green bacteria. The third part turns to energy transfer and electron transport, discussing modeling approaches, quantum aspects, photoinduced electron transfer, and redox potential modulation, followed by a section on experimental spectroscopy in light harvesting research. The concluding final section includes chapters on artificial photosynthesis, with topics such as use of cyanobacteria and algae for sustainable energy production. Robert Croce is Head of the Biophysics Group and full professor in biophysics of photosynthesis/energy at Vrije Universiteit, Amsterdam. Rienk van Grondelle is full professor at Vrije Universiteit, Amsterdam. Herbert van Amerongen is full professor of biophysics in the Department of Agrotechnology and Food Sciences at Wageningen University, where he is also director of the MicroSpectroscopy Research Facility. Ivo van Stokkum is associate professor in the Department of Physics and Astronomy, Faculty of Sciences, at Vrije Universiteit, Amsterdam.
Author: B.R. Green
Publisher: Springer Science & Business Media
ISBN: 9401720878
Category : Science
Languages : en
Pages : 533
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Book Description
Light-Harvesting Antennas in Photosynthesis is concerned with the most important process on earth - the harvesting of light energy by photosynthetic organisms. This book provides a comprehensive treatment of all aspects of photosynthetic light-harvesting antennas, from the biophysical mechanisms of light absorption and energy transfer to the structure, biosynthesis and regulation of antenna systems in whole organisms. It sets the great variety of antenna pigment-protein complexes in their evolutionary context and at the same time brings in the latest hi-tech developments. The book is unique in the degree to which it emphasizes the integration of molecular biological, biochemical and biophysical approaches. Overall, a well-organized, understandable, and comprehensive volume. It will be a valuable resource for both graduate students and their professors, and a helpful library reference book for undergraduates.
Author: Satyen Saha
Publisher: BoD – Books on Demand
ISBN: 9535104462
Category : Science
Languages : en
Pages : 298
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Book Description
There have been various comprehensive and stand-alone text books on the introduction to Molecular Photochemistry which provide crystal clear concepts on fundamental issues. This book entitled "Molecular Photochemistry - Various Aspects" presents various advanced topics that inherently utilizes those core concepts/techniques to various advanced fields of photochemistry and are generally not available. The purpose of publication of this book is actually an effort to bring many such important topics clubbed together. The goal of this book is to familiarize both research scholars and post graduate students with recent advancement in various fields related to Photochemistry. The book is broadly divided in five parts: the photochemistry I) in solution, II) of metal oxides, III) in biology, IV) the computational aspects and V) applications. Each part provides unique aspect of photochemistry. These exciting chapters clearly indicate that the future of photochemistry like in any other burgeoning field is more exciting than the past.
Author: Barbara Demmig-Adams
Publisher: Springer
ISBN: 9789402406283
Category : Science
Languages : en
Pages : 0
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Book Description
Harnessing the sun’s energy via photosynthesis is at the core of sustainable production of food, fuel, and materials by plants, algae, and cyanobacteria. Photosynthesis depends on photoprotection against intense sunlight, starting with the safe removal of excess excitation energy from the light-harvesting system, which can be quickly and non-destructively assessed via non-photochemical quenching of chlorophyll fluorescence (NPQ). By placing NPQ into the context of whole-organism function, this book aims to contribute towards identification of plant and algal lines with superior stress resistance and productivity. By addressing agreements and open questions concerning photoprotection’s molecular mechanisms, this book contributes towards development of artificial photosynthetic systems. A comprehensive picture –from single molecules to organisms in ecosystems, and from leading expert’s views to practical information for non-specialists on NPQ measurement and terminology – is presented.
Author: Alexander V. Ruban
Publisher: John Wiley & Sons
ISBN: 1118447603
Category : Science
Languages : en
Pages : 412
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Book Description
The proteins that gather light for plant photosynthesis are embedded within cell membranes in a site called the thylakoid membrane (or the "photosynthetic membrane"). These proteins form the light harvesting antenna that feeds with energy a number of vital photosynthetic processes such as water oxidation and oxygen evolution, the pumping of protons across the thylakoid membranes coupled with the electron transport chain of the photosystems and cytochrome b6f complex, and ATP synthesis by ATP synthase utilizing the generated proton gradient. The Photosynthetic Membrane: Molecular Mechanisms and Biophysics of Light Harvesting is an introduction to the fundamental design and function of the light harvesting photosynthetic membrane, one of the most common and most important structures of life. It describes the underlying structure of the membrane, the variety and roles of the membrane proteins, the atomic structures of light harvesting complexes and their macromolecular assemblies, the molecular mechanisms and dynamics of light harvesting and primary energy transformations, and the broad range of adaptations to different light environments. The book shows, using the example of the photosynthetic membrane, how complex biological structures utilize principles of chemistry and physics in order to carry out biological functions. The Photosynthetic Membrane: Molecular Mechanisms of Light Harvesting will appeal to a wide audience of undergraduate and postgraduate students as well as researchers working in the fields of biochemistry, molecular biology, biophysics, plant science and bioengineering.
Author: Herbert van Amerongen
Publisher: World Scientific
ISBN: 9789810232801
Category : Science
Languages : en
Pages : 612
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Book Description
Excitons are considered as the basic concept used by describing the spectral properties of photosynthetic pigment-protein complexes and excitation dynamics in photosynthetic light-harvesting antenna and reaction centers. Following the recently obtained structures of a variety of photosynthetic pigment-protein complexes from plants and bacteria our interest in understanding the relation between structure, function and spectroscopy has strongly increased. These data demonstrate a short interpigment distance (of the order of 1 nm or even smaller) and/or a highly symmetric (ring-like) arrangement of pigment molecules in peripheral light-harvesting complexes of photosynthetic bacteria. Books which were devoted to the exciton problem so far mainly considered the spectral properties of molecular crystals. However, the small size of these pigment aggregates in the pigment-protein complexes as well as the role of the protein, which is responsible for the structural arrangement of the complex, clearly will have a dramatic influence on the pigment spectra and exciton dynamics. All these aspects of the problem are considered in this book. Exciton theory is mainly considered for small molecular aggregates (dimers, ring-like structures etc.). Together with the theoretical description of the classical conceptual approach, which mainly deals with polarization properties of the absorption and fluorescence spectra, the nonlinear femtosecond spectroscopy which is widely used for investigations now is also discussed. A large part of the book demonstrates the excitonic effects in a multitude of photosynthetic pigment-protein complexes and how we can understand these properties on the basis of the exciton concept.
Author: Abderrazzak Douhal
Publisher: World Scientific
ISBN: 9810248660
Category : Science
Languages : en
Pages : 854
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Book Description
This book contains important contributions from top international scientists on the-state-of-the-art of femtochemistry and femtobiology at the beginning of the new millennium. It consists of reviews and papers on ultrafast dynamics in molecular science.The coverage of topics highlights several important features of molecular science from the viewpoint of structure (space domain) and dynamics (time domain). First of all, the book presents the latest developments, such as experimental techniques for understanding ultrafast processes in gas, condensed and complex systems, including biological molecules, surfaces and nanostructures. At the same time it stresses the different ways to control the rates and pathways of reactive events in chemistry and biology. Particular emphasis is given to biological processes as an area where femtodynamics is becoming very useful for resolving the structural dynamics from techniques such as electron diffraction, and X-ray and IR spectroscopy. Finally, the latest developments in quantum control (in both theory and experiment) and the experimental pulse-shaping techniques are described.
