Download or read book Spectroscopic and Theoretical Studies of T1 Cu CuA and Cytochrome C written by Xiangjin Xie and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Metal sites that are known to be involved in biological electron transfer (ET) include Type 1 Copper (T1 Cu), CuA, cytochromes, and the 1-, 2-, 3-, and 4-iron sulfur centers (rubredoxin, ferredoxins, and high potential iron-sulfur proteins (HiPIPs)). These ET sites generally exhibit unusual spectroscopic features reflecting novel geometric and electronic structures that contribute to function. My focuses are on T1 Cu, CuA, cytochrome c proteins utilizing a wide-range of spectroscopies combined with density functional calculations to understand active site electronic structures, the origin of their geometric structures, and possible contributions to function. Five major achievements are: 1) defined the temperature dependent absorption feature of T1 Cu site in nitrite reductase (NIR) and provided insight into the entatic/rack nature of the blue Cu site in plastocyanin; 2) addressed the interesting absorption features of the T1 Cu site in P. pantotrophus pseudoazurin and demonstrated the spectral probes of the weak axial ligation in metalloprotein; 3) resolved a two-state issue in the mixed-valence binuclear CuA centers in cytochrome c oxidases (CcO) and nitrous oxide reductases (N2O) by a combination of density functional calculations and spectroscopy analyses, and evaluated proteins role in CuA sites and their contributions to ET function; 4) determined that the Cu-Cu interaction in CuA keeps the site delocalized even upon loss of a Histidine (NHis) ligand due to protonation, and defined the contribution of [sigma] delocalization to efficient ET; 5) investigated the nature of the Fe-SMet bond in ferricytochrome c. (1) Thermodynamic Equilibrium between Blue and Green Copper Sites and the Role of the Protein in Controlling Function Spectroscopies and density functional theory calculations indicate that there are large temperature-dependent absorption spectral changes present in green nitrite reductases (NiRs) due to a thermodynamic equilibrium between a green and a blue type 1 (T1) copper site. The axial methionine (Met) ligand is unconstrained in the oxidized NiRs, which results in an enthalpically favored ([delta]H [approximately equal to] 4.6 kcal/mol) Met-bound green copper site at low temperatures, and an entropically favored (T[delta]S [approximately equal to] 4.5 kcal/mol, at room temperature) Met-elongated blue copper site at elevated temperatures. In contrast to the NiRs, the classic blue copper sites in plastocyanin and azurin show no temperature-dependent behavior, indicating that a single species is present at all temperatures. For these blue copper proteins, the polypeptide matrix opposes the gain in entropy that would be associated with the loss of the weak axial Met ligand at physiological temperatures by constraining its coordination to copper. The potential energy surfaces of Met binding indicate that it stabilizes the oxidized state more than the reduced state. This provides a mechanism to tune down the reduction potential of blue copper sites by> 200 mV. (2) Variable Temperature Spectroscopic Study on Pseudoazurin: Effects of Protein Constraints on the Blue Cu Site. The T1 copper site of Paracoccus pantotrophus pseudoazurin exhibits significant absorption intensity in both the 450 and 600 nm regions. These are [sigma] and [pi] SCys to Cu2+ charge transfer (CT) transitions. The temperature dependent absorption, EPR, and resonance Raman (rR) vibrations enhanced by these bands indicate that a single species is present at all temperatures. This contrasts the temperature dependent behavior of the T1 center in nitrite reductase, which has a thioether ligand that is unconstrained by the protein. The lack of temperature dependence in the T1 site in pseudoazurin indicates the presence of a protein constraint similar to the blue Cu site in plastocyanin where the thioether ligand is constrained at 2.8 Å. However, plastocyanin exhibits only [pi] CT. This spectral difference between pseudoazurin and plastocyanin reflects a coupled distortion of the site where the axial thioether in pseudoazurin is also constrained, but at a shorter Cu--SMet bond length. This leads to an increase in the Cu2+--SCys bond length, and the site undergoes a partial tetragonal distortion in pseudoazurin. Thus, its ground state wavefunction has both [sigma] and [pi] character in the Cu2+--SCys bond. (3) The Two State Issue in the Mixed-Valence Binuclear CuA Center in Cytochrome c Oxidase and N2O Reductase For the CuA site in the protein, the ground and lowest energy excited-states are [sigma]u* and [pi]u, respectively, denoting the types of Cu-Cu interactions. EPR data on CuA proteins show a low g[vertical line][vertical line] value of 2.19 deriving from spin-orbital coupling between [sigma]u* and [pi]u, which requires an energy gap between [sigma]u* and [pi]u of 3000-4500 cm-1. On the other hand, from paramagnetic NMR studies, it has been observed that the first excited-state is thermally accessible and the energy gap between the ground state and the thermally accessible state is 350 cm-1. This study addressed this apparent discrepancy and evaluated the roles of the two electronic states, [sigma]u* and [pi]u, in electron transfer (ET) of CuA. The potential energy surface calculations show that both NMR and EPR results are consistent within the electronic/geometric structure of CuA. The anti-Curie behavior observed in paramagnetic NMR studies of CuA results from the thermal equilibrium between the [sigma]u* and [pi]u states, which are at very close energies in their respective equilibrium geometries. Alternatively, the EPR g-value analysis involves the [sigma]u* ground state in the geometry with a short dCu-Cu where the [pi]u state is a Frank-Condon excited-state with the energy of 3200 cm-1. The protein environment plays a role in maintaining CuA in the [sigma]u* state as a lowest-energy state with the lowest reorganization energy and high-covalent coupling to the Cys and His ligands for efficient intra- and intermolecular ET with a low-driving force. (4) Perturbations to the Geometric and Electronic Structure of the CuA Site: Factors that Influence Delocalization and their Contributions to Electron Transfer Using a combination of electronic spectroscopies and DFT calculations, the effect of pH perturbation on the geometric and electronic structure of the CuA site has been defined. Descriptions are developed for high pH (pH = 7) and low pH (pH = 4) forms of CuA azurin and its H120A mutant which address the discrepancies concerning the extent of delocalization indicated by multifrequency EPR and ENDOR data. Our resonance Raman and MCD spectra demonstrate that the low pH and H120A mutant forms are essentially identical and are the perturbed forms of the completely delocalized high pH CuA site. However, in going from high pH to low pH, a seven-line hyperfine coupling pattern associated with complete delocalization of the electron (S = 1/2) over two Cu coppers (ICu = 3/2) changes into a four-line pattern reflecting apparent localization. DFT calculations show that the unpaired electron is delocalized in the low pH form and reveal that its four-line hyperfine pattern results from the large EPR spectral effects of 1% 4s orbital contribution of one Cu to the ground-state spin wave function upon protonative loss of its His ligand. The contribution of the Cu-Cu interaction to electron delocalization in this low symmetry protein site is evaluated, and the possible functional significance of the pH-dependent transition in regulating proton-coupled electron transfer in cytochrome c oxidase is discussed. (5) The Fe-Smet Bond in Ferricytochrome c DFT calculations calibrated with experiment data were used to define the nature of the Fe-SMet bond in ferricytochrome c. This is inspired by the studies of NiR.
Download or read book Spectroscopic and Theoretical Studies of Oxygen Intermediates and Catalytic O2 Reduction in the Multicopper Oxidases written by Jungjoo Yoon and published by . This book was released on 2007 with total page 512 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Spectroscopic and Theoretical Studies of Perturbed Blue Copper Proteins written by Louis B. LaCroix and published by . This book was released on 1997 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Transition Metals and Sulfur A Strong Relationship for Life written by Martha Sosa Torres and published by Walter de Gruyter GmbH & Co KG. This book was released on 2020-04-06 with total page 610 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metal Ions in Life Sciences links coordination chemistry and biochemistry in their widest sense and thus increases our understanding of the relationship between the chemistry of metals and life processes; in fact, it is an old wisdom that metals are indispensable for life. The series reflects the interdisciplinary nature of Biological Inorganic Chemistry and coordinates the efforts of scientists in numerous interconnecting research fields.
Download or read book American Chemical Society Directory of Graduate Research 1987 written by American Chemical Society, Committee on Professional Training Staff and published by . This book was released on 1987 with total page 1390 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Annual Review written by 岡崎国立共同研究機構分子科学研究所 and published by . This book was released on 1991 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Biomolecular EPR Spectroscopy written by Wilfred Raymond Hagen and published by CRC Press. This book was released on 2008-12-22 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comprehensive, Up-to-Date Coverage of Spectroscopy Theory and its Applications to Biological SystemsAlthough a multitude of books have been published about spectroscopy, most of them only occasionally refer to biological systems and the specific problems of biomolecular EPR (bioEPR). Biomolecular EPR Spectroscopy provides a practical introduction t
Download or read book Metal Sites in Proteins and Models written by H.A.O. Hill and published by Springer Science & Business Media. This book was released on 1999-04-01 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: Biological chemistry is a major frontier of inorganic chemistry. Three special volumes devoted to Metal Sites in Proteins and Models address the questions: how unusual ("entatic") are metal sites in metalloproteins and metalloenzymes compared to those in small coordination complexes? and if they are special, how do polypeptide chains and co-factors control this? The chapters deal with iron, with metal centres acting as Lewis acids, metals in phosphate enzymes, with vanadium, and with the wide variety of transition metal ions which act as redox centres. They illustrate in particular how the combined armoury of genetics and structure determination at the molecular level are providing unprecedented new tools for molecular engineering.
Download or read book Spectroscopic Methods in Bioinorganic Chemistry written by Edward I. Solomon and published by . This book was released on 1998 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains recent advances in spectrographic methods, including EPR, magnetic Mossbauer, paramagnetic and multi-D NMR, metalloprotein crystallography, EAS, magnetic circular dichroism, resonance Raman, X-ray absorption spectroscopy, and electron structure calculations. The book concentrates on topics where spectrographic methods have had a major impact, such as electron transfer, cluster interactions, intermediates, and definition of active site structure, and it includes a thorough tutorial on basic methods.
Download or read book Bioinorganic Chemistry of Copper written by K.D. Karlin and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 510 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bioinorganic Chemistry of Copper focuses on the vital role of copper ions in biology, especially as an essential metalloenzyme cofactor. The book is highly interdisciplinary in its approach--the outstanding list of contributors includes coordination chemists, biochemists, biophysicists, and molecular biologists. Chapters are grouped into major areas of research interest in inorganic copper chemistry, spectroscopy, oxygen chemistry, biochemistry, and molecular biology. The book also discusses basic research of great potential importance to pharmaceutical scientists. This book is based on the first Johns Hopkins University Copper Symposium, held in August 1992. Researchers in chemistry, biochemistry, molecular biology, and medicinal chemistry will find it to be an essential reference on its subject.
Download or read book Magnetic Circular Dichroism Spectroscopy written by W. Roy Mason and published by John Wiley & Sons. This book was released on 2007-07-09 with total page 237 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book is a technical guide for chemists and spectroscopists, and presents a concise description of magnetic circular dichroism (MCD) spectroscopy and how it has advanced the interpretation of molecular electronic spectra. Provides a practical guide to utilizing MCD spectroscopy for chemists starting in the field Written by an expert with over twenty years of experience in the field Helps the reader to visualize the optical spectroscopic effects presented by MCD measurements Includes practical considerations for experimental MCD measurements based on the author's experience Written as a general discussion of the subject matter, with illustrative examples provided and discussed in the case studies to show the breadth of application of MCD measurements.
Download or read book Index to Theses with Abstracts Accepted for Higher Degrees by the Universities of Great Britain and Ireland and the Council for National Academic Awards written by and published by . This book was released on 2003 with total page 716 pages. Available in PDF, EPUB and Kindle. Book excerpt: Theses on any subject submitted by the academic libraries in the UK and Ireland.
Download or read book Biochemistry written by David E. Metzler and published by Elsevier. This book was released on 2003-05-04 with total page 1063 pages. Available in PDF, EPUB and Kindle. Book excerpt: Biochemistry: The Chemical Reactions of Living Cells is a well-integrated, up-to-date reference for basic chemistry and underlying biological phenomena. Biochemistry is a comprehensive account of the chemical basis of life, describing the amazingly complex structures of the compounds that make up cells, the forces that hold them together, and the chemical reactions that allow for recognition, signaling, and movement. This book contains information on the human body, its genome, and the action of muscles, eyes, and the brain. * Thousands of literature references provide introduction to current research as well as historical background * Contains twice the number of chapters of the first edition * Each chapter contains boxes of information on topics of general interest
Download or read book Molecular Evolution written by Roderick D.M. Page and published by John Wiley & Sons. This book was released on 2009-07-14 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of evolution at the molecular level has given the subject of evolutionary biology a new significance. Phylogenetic 'trees' of gene sequences are a powerful tool for recovering evolutionary relationships among species, and can be used to answer a broad range of evolutionary and ecological questions. They are also beginning to permeate the medical sciences. In this book, the authors approach the study of molecular evolution with the phylogenetic tree as a central metaphor. This will equip students and professionals with the ability to see both the evolutionary relevance of molecular data, and the significance evolutionary theory has for molecular studies. The book is accessible yet sufficiently detailed and explicit so that the student can learn the mechanics of the procedures discussed. The book is intended for senior undergraduate and graduate students taking courses in molecular evolution/phylogenetic reconstruction. It will also be a useful supplement for students taking wider courses in evolution, as well as a valuable resource for professionals. First student textbook of phylogenetic reconstruction which uses the tree as a central metaphor of evolution. Chapter summaries and annotated suggestions for further reading. Worked examples facilitate understanding of some of the more complex issues. Emphasis on clarity and accessibility.
Download or read book Color Atlas of Biochemistry written by Jan Koolman and published by Thieme. This book was released on 2011-01-01 with total page 482 pages. Available in PDF, EPUB and Kindle. Book excerpt: Totally revised and expanded, the Color Atlas of Biochemistry presents the fundamentals of human and mammalian biochemistry on 215 stunning color plates.Alongside a short introduction to chemistry and the classical topics of biochemistry, the 2nd edition covers new approaches and aspects in biochemistry, such as links between chemical structure and biological function or pathways for information transfer, as well as recent developments and discoveries, such as the structures of many new important molecules. Key features of this title include:- The unique combination of highly effective color graphics and comprehensive figure legends;- Unified color-coding of atoms, coenzymes, chemical classes, and cell organelles that allows quick recognition of all involved systems;- Computer graphics provide simulated 3D representation of many important molecules.This Flexibook is ideal for students of medicine and biochemistry and a valuable source of reference for practitioners.
Download or read book Fundamentals of Medicinal Chemistry written by Gareth Thomas and published by John Wiley & Sons. This book was released on 2004-04-20 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides a concise introduction to the chemistry of therapeutically active compounds, written in a readable and accessible style. The title begins by reviewing the structures and nomenclature of the more common classes of naturally occurring compounds found in biological organisms. An overview of medicinal chemistry is followed by chapters covering the discovery and design of drugs, pharmacokinetics and drug metabolism, The book concludes with a chapter on organic synthesis, followed by a brief look at drug development from the research stage through to marketing the final product. The text assumes little in the way of prior biological knowledge. relevant biology is included through biological topics, examples and the Appendices. Incorporates summary sections, examples, applications and problems Each chapter contains an additional summary section and solutions to the questions are provided at the end of the text Invaluable for undergraduates studying within the chemical, pharmaceutical and life sciences.
Download or read book Principles of Bioenergetics written by Vladimir P. Skulachev and published by Springer Science & Business Media. This book was released on 2012-12-15 with total page 435 pages. Available in PDF, EPUB and Kindle. Book excerpt: Principles of Bioenergetics summarizes one of the quickly growing branches of modern biochemistry. Bioenergetics concerns energy transductions occurring in living systems and this book pays special attention to molecular mechanisms of these processes. The main subject of the book is the "energy coupling membrane" which refers to inner membranes of intracellular organelles, for example, mitochondria and chloroplasts. Cellular cytoplasmic membranes where respiratory and photosynthetic energy transducers, as well as ion-transporting ATP-synthases (ATPases) are also part of this membrane. Significant attention is paid to the alternative function of mitochondria as generators of reactive oxygen species (ROS) that mediate programmed death of cells (apoptosis and necrosis) and organisms (phenoptosis). The latter process is considered as a key mechanism of aging which may be suppressed by mitochondria-targeted antioxidants.
