Download or read book Modeling the Active Sites of Non heme Diiron Metalloproteins with Sterically Hindered Carboxylates and Syn N Donor Ligands written by Simone Friedle and published by . This book was released on 2009 with total page 233 pages. Available in PDF, EPUB and Kindle. Book excerpt: (Cont.) These Mossbauer parameters are comparable to those observed for a peroxo intermediate formed in the reaction of reduced toluene/o-xylene monooxygenase hydroxylase (ToMOH) with dioxygen. Resonance Raman studies reveal an unusually low-energy 0-0 stretching mode in the peroxo intermediate that is consistent with a short diiron distance. Although peroxodiiron(lll) intermediates generated from 6, 7, and 8 are poor O-atom transfer catalysts, they display highly efficient catalase activity, with turnover numbers up to 10,000. In contrast to hydrogen peroxide reactions of diiron(Ill) complexes that lack a dinucleating ligand, the intermediates generated here could be reformed in significant quantities after a second addition of H20 2, as observed spectroscopically and by mass spectrometry. Appendix 1. Supporting Tables and Figures for Chapter 2 Appendix 2. Supporting Information for Chapter 4 Appendix 3. Synthesis of Triptycene Carboxylate-Bridged Dimetallic Complexes with First Row Transition Metals The synthesis and structural characterization of dimetallic complexes of the type [M2(1t-02CTrp) 4(THF)2] (M = Mn, Co, Ni, Cu, Zn) supported by triptycenecarboxylate ligands ( -O2CTrp) is described. Appendix 4. Synthesis and Structure of a Molecular Ferrous Wheel, [Fe(0 2CH)(O 2CArPro)(1,4-dioxane)]6 The structural characterization of a novel, hexanuclear iron(ll) compound with the carboxylate ArPrOCO2- is described.

Download or read book Modeling the Active Sites of Diiron and Dicopper Metalloproteins with Napthyridine Phthalazine and Diethynylbenzene based Ligands written by Jane Kuzelka and published by . This book was released on 2003 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chapter 1. Bio-Inspired Reactions of Diiron Centers with Dioxygen A variety of biological systems employ carboxylate-bridged diiron centers to achieve substrate oxidation using dioxygen, and numerous small molecule model compounds have been synthesized in order to mimic this chemistry in the absence of a protein scaffold. In this introductory chapter, a brief overview is presented of ligand systems that have been used to prepare diiron complexes, and the subsequent oxidation chemistry of these systems is outlined. Chapter 2. Carboxylate, Phosphodiester, and Hydroxide-Bridged Diiron(II) Complexes with a Sterically Hindered Phthalazine Ligand The synthesis and crystallographic characterization of a series of diiron(II) complexes with a sterically hindered bridging phthalazine ligand are presented. The compounds [Fe2(Ph4bdptz)([mu]-O2CR)2]2+ (R = CH3 (3); C2H5 (4); CH2Ph (5); t-C4H9 (6)), [Fe2(Ph4bdptz)([mu]-O2P(OPh)2)2]2+ (7), and [Fe2(Ph4bdptz) ([mu]-OH)(MeCN)2]3+ (8) were prepared as small molecule models of the catalytic sites in non-heme carboxylate-bridged diiron enzymes. The phenyl rings of Ph4bdptz form a hydrophobic size-constrained pocket in which additional ligands can be accommodated, and they block the possible formation of tetranuclear species. As the steric bulk of the ancillary ligands is increased, the carboxylates shift from a syn, anti to a syn, syn coordination mode, and the Mossbauer spectra of the diiron(II) compounds clearly reflect the symmetry of the iron coordination environment. The oxidation chemistry of the diiron(II) compounds is presented.

Download or read book Use of Sterically Hindered Carboxylate Ligands to Model Structural and Functional Features of Dioxygen activating Centers in Non heme Diiron Enzymes written by Dongwhan Lee and published by . This book was released on 2002 with total page 888 pages. Available in PDF, EPUB and Kindle. Book excerpt: (Cont.) By using sterically hindered carboxylate ligands, 2,6-di(p-tolyl)benzoate (ArTolCO2- ) and 2,6-di(4-tert-butylphenyl)benzoate (Ar4-tBPhCO2- ), series of four-, five-, and six-coordinate iron(II) complexes were synthesized. The compounds are [Fe(O2CArTol)2(1-BnIm)2] (3), [Fe(O2CArTol)2(1-MeBzIm)2] (4), [Fe(02C-Ar4-tBuPh)2(2,2'-bipy)2] (5), [Fe(O2CArTol)2(TMEDA)] (6), and [Fe(O2CArTol)2(BPTA)] (7). Structural analyses of 3-7 revealed that the overall stereochemistry of the [Fe(O2CAr')2Ln] units is dictated by electronic and steric factors of the N-donor ligands (L), as well as by the flexible coordination of the carboxylate ligands. Distinctive MOss-Bauer parameters obtained for these and related compounds facilitated the spectral assignment of a diiron(II) complex having asymmetric metal sites, [Fe2(p-02CArTol)3(2CArTol)(2,6-lutidine)] (2). Well-defined mononuclear iron carboxylate complexes thus may serve as subsite models for higher nuclearity species in both synthetic and biological systems. Chapter III. Functional Mimic of Dioxygen-Activating Centers in Non-Heme Diiron Enzymes: Mechanistic Implications of Paramagnetic Intermediates in the Reactions between Diiron(II) Complexes and Dioxygen Tetracarboxylate diiron(II) complexes, [Fe2( -O02CArTOl)2(02CArToll)2(C5H5N)2] (la) and [Fe2(Pl-02CArTol)4(4-tBuC5H4N)2] (2a), where ArTloCO2- = 2,6-di(p-tolyl)benzoate, react with 02 in CH2C12 at -78 C to afford deep green intermediates ...

Download or read book Oxidation of Substrates Tethered to N donor Ligands for Modeling Non heme Diiron Enzyme Active Sites written by Emily Carrig Carson and published by . This book was released on 2005 with total page 231 pages. Available in PDF, EPUB and Kindle. Book excerpt: (Cont.) 2-, 3-, or 4-Diphenylphosphino moieties incorporated into a pyridine ligand (2-, 3-, or 4-Ph2Ppy) were allowed to react with the preassembled diiron(II) complex ..., where ... is a sterically hindered 2,6-di(p-tolyl)- or 2,6-di(p-fluorophenyl)benzoate (R = Tol or 4-FPh). Triply-, doubly-, and tetrabridged compounds ... (1) ... (2) ... (3) ... (4) resulted and were characterized crystallographically. Exposure of 1 - 4 to dioxygen revealed both stoichiometric and catalytic phosphine oxidation. Oxidation of 4 in CH2C12 affords ... (6), which contains the biologically relevant [Fe2([mu]-OH)2([mu]-O2CR)] 3 core. This reaction is sensitive to the choice of carboxylate ligands, however, since the p-tolyl analog 1 yielded a hexanuclear species, 5, upon oxidation.

Download or read book Dissertation Abstracts International written by and published by . This book was released on 2004 with total page 858 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Model Complexes for Active Sites of Diiron Metalloproteins Dioxygen Reactivity and Water Effects written by Sungho Yoon and published by . This book was released on 2004 with total page 301 pages. Available in PDF, EPUB and Kindle. Book excerpt: (Cont.) tetrairon(II) cubane complex was identified and structurally characterized. Chapter 4: Synthesis and Characterization of [Fe2 ... CR)]3 and [Fe2 ... CR)]3+ Complexes with Carboxylate-Rich Metal Coordination Environment as Models for Diiron Centers in Oxygen-Dependent Non-Heme Enzymes. Utilizing hydrogen bonding interactions and sterically bulky carboxylates, synthetic routes were developed to prepare the mononuclear iron(II) complexes with the vacant coordination sites for O2 binding. Reactions of such complexes with O2 resulted in rare asymmetric complexes having an [Fe2 ... CR)]3+ or [Fe2 ... CR)]3+ unit. These diiron(III) complexes with carboxylate-rich metal coordination environments reproduce the diiron(III) cores housed in four-helix bundles found in nature. Compound 3, which replicates the [Fe2 ... CR)] core of sMMOH[ox], shares several physical properties with the enzyme, electronic transitions, Mossbauer spectra, and magnetic exchange interactions. On the other hand, the structure of 4, ([mu]-oxo)([mu]-carboxylato)diiron(III) complex, mimics the diiron(III) sites of RNR-R2. The electronic and Mbssbauer spectral transitions of 4 are typical of diiron(III) complexes with an Fe-O-Fe moiety. Magnetic exchange coupling interaction between the two iron atoms is within the expected range for oxo-bridged diiron(III) sites. These results demonstrate how the diiron(III) structures in different metalloproteins, namely, the [mu]-oxo cores of RNR-R2 and the [mu]-dihydroxo unit in MMOH, can be replicated by subtle changes in ligand composition ...

Download or read book Metalloprotein Active Site Assembly written by Michael K. Johnson and published by John Wiley & Sons. This book was released on 2017-08-30 with total page 424 pages. Available in PDF, EPUB and Kindle. Book excerpt: Summarizes the essential biosynthetic pathways for assembly of metal cofactor sites in functional metalloproteins Metalloprotein Active Site Assembly focuses on the processes that have evolved to orchestrate the assembly of metal cofactor sites in functional metalloproteins. It goes beyond the simple incorporation of single metal ions in a protein framework, and includes metal cluster assembly, metal-cofactor biosynthesis and insertion, and metal-based post-translational modifications of the protein environments that are necessary for function. Several examples of each of these areas have now been identified and studied; the current volume provides the current state-of-the-art understanding of the processes involved. An excellent companion to the earlier book in this series Metals in Cells—which discussed both the positive and negative effects of cellular interactions with metals—this comprehensive book provides a diverse sampling of what is known about metalloprotein active site assembly processes. It covers all major biological transition metal components (Mn, Fe, Co, Ni, Mo), as well as the other inorganic components, metal-binding organic cofactors (e.g., heme, siroheme, cobalamin, molybdopterin), and post-translationally modified metal binding sites that make up the patchwork of evolved biological catalytic sites. The book compares and contrasts the biosynthetic assembly of active sites involving all biological metals. This has never been done before since it is a relatively new, fast-developing area of research. Metalloprotein Active Site Assembly is an ideal text for practitioners of inorganic biochemistry who are studying the biosynthetic pathways and gene clusters involved in active site assembly, and for inorganic chemists who want to apply the concepts learned to potential synthetic pathways to active site mimics.

Download or read book Coordination Chemistry of Mononuclear Non heme Iron Oxygenase Enzymes written by Paul C. Tarves and published by . This book was released on 2013 with total page 468 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Mononuclear non-heme iron oxygenase (MNO) enzymes utilize ferrous iron and dioxygen to perform a variety of thermodynamically challenging reactions at standard temperatures and pressures. The potent oxidizing power of these enzymatic systems has led to increased interest from the bioinorganic and synthetic organic communities. Presented herein is the preparation and characterization of an a-keto acid dependent synthetic system that closely models the active site electronic and dioxygen reactivity properties of the Fe II/a-ketoglutarate dependent class of MNH iron oxygenase enzymes. The ferrous complex utilized possesses a facially coordinating N,N,O- donor ligand reminiscent of a common active site motif observed for MNO iron enzymes. The labile coordination sites opposite the ligand framework allow for the ligation of exogenous a-keto acid cofactor as well as the binding and activation of dioxygen. The coordination of exogenous a-keto acid cofactor has been shown to greatly enhance the rate of dioxygen reactivity of the ferrous complex and lead to the catalytic decarboxylation of the cofactor. The enhancement in rate is attributed to the coupling of the dioxygen reduction step to the oxidative decarboxylation of the bound cofactor, which is a thermodynamically favorable process. The oxidative decarboxylation pathway suggests the formation of a high valent iron-oxo intermediate, which has been further supported by the concentration dependence of solvent oxidation during catalysis. The mechanism of dioxygen reactivity was further probed by Hammett analysis using substituted aromatic a-keto acid cofactors. The data presented suggest that the model system prepared proceeds via a biomimetic mechanism capable of catalytic dioxygen activation and substrate oxidation under ambient conditions. Investigation of differential carboxylate and phenolate ligation as it pertains to MNO iron enzymes is also reported. The synthesis and characterization of both ferrous and ferric compounds containing ligands with similar ethylene diamine backbones and either one or two phenolate moities: 2-(((2-(dimethylamino)ethyl)(methyl)amino)-methyl)phenol (N2O1-Ph) and 2,2'-((ethane-1,2-diylbis(methylazanediyl))bis-(methylene))diphenol (N2O2-Ph). The replacement of carboxylate moiety with a phenolate led to a significant decrease in reduction potential and subsequent enhancement in dioxygen sensitivity. This observation may provide insight into the reactivity of other iron containing enzymes with coordinated tyrosine residues, such as intradiol catechol dioxygenases.

Download or read book Steric Effects on the Stability and Reactivity of Model Complexes of Non heme Diiron Proteins and Ferritin written by Do Trong Bao and published by . This book was released on 2001 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Handbook of Metalloproteins written by Albrecht Messerschmidt and published by Wiley. This book was released on 2001-08-16 with total page 1500 pages. Available in PDF, EPUB and Kindle. Book excerpt: "it is a pleasure just to read this handsome and carefully produced work" Angewandte Chemie 2002 "...the Handbook of Metalloproteins is highly recommended as a resource for bioinorganic chemistry. It will have lasting value for researchers in the field..." The Alchemist - Chemweb In recent years, the analysis and classification of metalloproteins at the interface between chemistry and biology has accelerated. Many developments and initiatives have taken place and this two-volume handbook provides a comprehensive, yet focussed, collection of 105 major metalloproteins. Content is presented in both a large format and full colour and covers the most relevant transition metals such as Iron, Nickel, Copper, Cobalt, Molybdenum, Manganese Tungsten and Vanadium. This is the first Handbook of Metalloproteins ever published and is comprised of articles written by renowned experts in the field. It draws together contributions from over two hundred internationally renowned researchers that include: Douglas Rees and Charles Stout as well as Nobel Prize winner Robert Huber. Each contribution is presented in a similar format and shows a ribbon plot of the overall 3D Structure on their first page, a representation of the metal active site and numerous other figures and tables underpinning the remarks. Comparative information is provided on different proteins and every entry has been extensively referenced to current literature. * First comprehensive handbook to cover the major metalloproteins * Presents structural and functional data in an organised manner * Incorporates full-colour representation of molecular structures throughout * Unifies information from molecular biology, enzymology, spectroscopy, biochemistry, chemistry, biophysics, macromolecular crystallography and structural biology * Includes comprehensive sections that cover: Functional Class, Occurrence, Amino Acid Sequence Information, Protein Production, Purification and Molecular Characterisation, Metal Content and Cofactors, Activity Test, Spectroscopy, 3D Structure, Functional Aspects.

Download or read book Principles of Bioinorganic Chemistry written by Stephen J. Lippard and published by University Science Books. This book was released on 1994 with total page 444 pages. Available in PDF, EPUB and Kindle. Book excerpt: The use of unnatural metals - which have been introduced into human biology as diagnostic probes and drugs - is another active area of tremendous medical significance.

Download or read book Iron containing Enzymes written by Sam P. De Visser and published by Royal Society of Chemistry. This book was released on 2011 with total page 463 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mononuclear iron containing enzymes are important intermediates in bioprocesses and have potential in the industrial biosynthesis of specific products. This book features topical review chapters by leaders in this field and its various sub-disciplines.

Download or read book The Chemistry of the Cyclopropyl Group NY Handling Set Only written by Zvi Rappoport and published by . This book was released on 1987 with total page 832 pages. Available in PDF, EPUB and Kindle. Book excerpt: The latest in a series of advanced treatises under the general editorship of Professor Saul Patai providing a comprehensive review of the chemistry of the cyclopropyl group including physical properties, analysis, reaction mechanisms and synthetic uses.

Download or read book Chemistry and Biochemistry of B12 written by Ruma Banerjee and published by John Wiley & Sons. This book was released on 1999-11-03 with total page 960 pages. Available in PDF, EPUB and Kindle. Book excerpt: A Definitive New Reference for the Latest Advances in B_12 Chemistry and Biochemistry Over the past decade, the field of B_12 research has been revolutionized by such major breakthroughs as the unraveling of the entire biosynthetic pathway for this important vitamin. This comprehensive compendium surveys the wealth of information that has accumulated, covering in one volume virtually all aspects of the field-from physical and inorganic chemistry to enzymology, microbiology, medicine, and diagnostic and therapeutic applications. Edited by Dr. Ruma Banerjee, a highly respected and active member of the B_12 community, this work provides B_12 researchers with a dependable and up-to-date reference on the subject. Leading authorities from five continents explore such new areas as the structural biology of B_12-dependent enzymes, free-radical-mediated reaction mechanisms, biosynthesis, and much more. The role of B_12 in nutrition and disease, and B_12 transport, are also thoroughly examined. Complete with color illustrations and extensive references, Chemistry and Biochemistry of B_12 is a one-of-a-kind resource for biochemists, biophysicists, spectroscopists, microbiologists, molecular biologists, and anyone with an interest in "nature's most beautiful cofactor."

Download or read book Biological Inorganic Chemistry written by Robert R. Crichton and published by Elsevier. This book was released on 2007-12-11 with total page 383 pages. Available in PDF, EPUB and Kindle. Book excerpt: The importance of metals in biology, the environment and medicine has become increasingly evident over the last twenty five years. The study of the multiple roles of metal ions in biological systems, the rapidly expanding interface between inorganic chemistry and biology constitutes the subject called Biological Inorganic Chemistry. The present text, written by a biochemist, with a long career experience in the field (particularly iron and copper) presents an introduction to this exciting and dynamic field. The book begins with introductory chapters, which together constitute an overview of the concepts, both chemical and biological, which are required to equip the reader for the detailed analysis which follows. Pathways of metal assimilation, storage and transport, as well as metal homeostasis are dealt with next. Thereafter, individual chapters discuss the roles of sodium and potassium, magnesium, calcium, zinc, iron, copper, nickel and cobalt, manganese, and finally molybdenum, vanadium, tungsten and chromium. The final three chapters provide a tantalising view of the roles of metals in brain function, biomineralization and a brief illustration of their importance in both medicine and the environment. Relaxed and agreeable writing style. The reader will not only fiind the book easy to read, the fascinating anecdotes and footnotes will give him pegs to hang important ideas on.Written by a biochemist. Will enable the reader to more readily grasp the biological and clinical relevance of the subject.Many colour illustrations. Enables easier visualization of molecular mechanismsWritten by a single author. Ensures homgeneity of style and effective cross referencing between chapters

Download or read book Biological Inorganic Chemistry written by Ivano Bertini and published by University Science Books. This book was released on 2007 with total page 794 pages. Available in PDF, EPUB and Kindle. Book excerpt: Part A.: Overviews of biological inorganic chemistry : 1. Bioinorganic chemistry and the biogeochemical cycles -- 2. Metal ions and proteins: binding, stability, and folding -- 3. Special cofactors and metal clusters -- 4. Transport and storage of metal ions in biology -- 5. Biominerals and biomineralization -- 6. Metals in medicine. -- Part B.: Metal ion containing biological systems : 1. Metal ion transport and storage -- 2. Hydrolytic chemistry -- 3. Electron transfer, respiration, and photosynthesis -- 4. Oxygen metabolism -- 5. Hydrogen, carbon, and sulfur metabolism -- 6. Metalloenzymes with radical intermediates -- 7. Metal ion receptors and signaling. -- Cell biology, biochemistry, and evolution: Tutorial I. -- Fundamentals of coordination chemistry: Tutorial II.

Download or read book Bioinorganic Chemistry written by D.P. Kessissoglou and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 422 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bioinorganic chemistry is primarily concerned with the role of metal atoms in biology and is a very active research field. However, even though such important structures of metalloenzymes are known, as the MoFeCo of nitrogenase, Cu or Mn superoxide dismutase and plastocyanin, the synthetic routes to the modelling of such centers remains a matter of acute scientific interest. Other metalloenzymes, such as the Mn center of the oxygen evolving complex of PSII, are still the focus of in-depth examination, both spectroscopic and structural. Another area of concern is the interaction between drugs and metals and metal ion antagonism. Understanding the chemistry of metal ions in biological systems will bring benefits in terms of understanding such problems as biomineralization and the production of advanced materials by micro-organisms. The 29 contributions to Bioinorganic Chemistry: An Inorganic Perspective of Life give an excellent summary of the state of the art in this field, covering areas from the NMR of paramagnetic molecules to the use of lanthanide porphyrins in artificial batteries.