Download or read book Modeling the Active Sites of Metalloenzymes with Thiolate Coordination written by Curtis Eugene Moore and published by . This book was released on 2007 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nitrile Hydratase (NHase) is a bacterial enzyme which catalyzes the hydrolysis of organic nitriles to their corresponding amides. The active site of NHase contains Fe (III) or Co(III) ions in an unusual coordination sphere containing 2 amide N atoms and three S donors. The research described herein is an attempt to model this active site using two different model systems: one that generates metal-coordinated imines, and one that generates metal-coordinated amides. Using 2,20́9-dithiodibenzaldehyde and derivatives of 2,20́9-dithiodisalicylic acid as reactants, several new and interesting metal coordinated imine and metal coordinated amide complexes have been synthesized. The synthesis and crystallization of several new organic and ligand species is discussed as well. The synthesis of a Co complex that resembles the active site of NHase is reported herein, along with several other new organometallic species. Also, two projects using computational chemistry are reported: one modeling trispyrazolylborate (Tp) complexes of iron and copper, and one modeling iron, manganese, and copper complexes of pentadentate imine/phenolate ligands. Complexes of Tp ligands with relatively bulky substituents in the 3-position are subject to isomerization through a borotropic shift. Computational chemistry has shed light on the energetics behind the borotropic shift. Calculations on the CO stretching frequency of several different TpCu(I)CO complexes have been carried out in an effort to match experimental data and generate predictive values for several other species not yet synthesized. This stretching frequency can generally be directly related to the electron withdrawing/donating character of the Tp ligand attached to the metal center. Pentdentate imine/phenolate ligands can coordinate to transition metals in a number of isomers. Computational chemistry has been used to shed light on the structural preferences of the iron, manganese, and copper species. These calculations were able to match the experimental data for crystallographically characterized species, and the metal complexes were shown to have specific structural preferences depending on the identity of the metal used.
Download or read book The Synthesis of Thiolate Ligands for Modeling the Active Sties of Metalloenzymes written by Christopher Gordon Oliveri and published by . This book was released on 2003 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Coordination Chemistry of Metalloenzymes written by I. Bertini and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 397 pages. Available in PDF, EPUB and Kindle. Book excerpt: Assembling a program in bioinorganic chemistry that is scientifi cally relevant, well defined, and self-consistent is not an easy task. In this attempt we decided to consider zinc enzymes, copper oxidases, cytochromes and cytochrome oxidase. The choice is in part due to the great attention that the current specialized literature devotes to these topics, which are now debated among chemists, biochemists, biophysicists, etc .. We believe that hydration reactions, hydrolytic and oxidative processes have much in common from the point of view of the reaction mechanisms, the comprehension of which represents a frontier of science. For these reasons these topics have been the subject of the NATO-ASI held at San Miniato, Pisa, Italy, from May 28 to June 8, 1982. We hope we can transfer here the main conclusions of what (we believe) was a very stimulating scientific meeting. We would like to thank the local saving bank, Cassa di Risparmio di San Miniato, for helping in many ways. The financial contribution from the European Research Office of the US Army, and from the Bruker Spectrospin s.r.l., Italy, is also acknowledged. The National Science Foundation of the United States has provided a travel grant to one of the participants from the U.S.A. We are grateful to the NATO Scientific Affairs Division which provided a grant to finance this Institute.
Download or read book Spectroscopic and Computational Studies of Metal thiolate Interactions in Metalloenzymes and Related Model Complexes written by Adam T. Fiedler and published by . This book was released on 2006 with total page 548 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Comprehensive Coordination Chemistry II written by J. A. McCleverty and published by Newnes. This book was released on 2003-12-03 with total page 11845 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comprehensive Coordination Chemistry II (CCC II) is the sequel to what has become a classic in the field, Comprehensive Coordination Chemistry, published in 1987. CCC II builds on the first and surveys new developments authoritatively in over 200 newly comissioned chapters, with an emphasis on current trends in biology, materials science and other areas of contemporary scientific interest.
Download or read book Metalloenzymes with Carboxamido N metal and Thiolato S metal Bonds written by Todd Christopher Harrop and published by . This book was released on 2004 with total page 930 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Transition Metal Thiolate Complexes written by Philip A. Stenson and published by . This book was released on 2005 with total page 556 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis and Studies of Models for Two Zinc containing Metallo enzymes written by Neville J. Curtis and published by . This book was released on 1981 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Several Zn[superscript ++] -containing meta 11o-enzymes are known in which histidine imidazole nitrogens are ligands to the active site zinc. Two such enzymes are alcohol dehydrogenase (ADH), containing one histidine and two cysteine sulphurs, and carbonic anhydrase (CA), containing three histidines coordinated to Zn[superscript ++]. Considerable effort has been applied to the synthesis and studies of small molecules which contain an imidazole (or pyridine), along with other ligating species as models which mimic the metal binding site and the enzyme process. The first chapter deals with the synthesis and physical studies of chelating ligands containing a basic nitrogen and two sulphurs as models for ADH. This enzyme catalyses the interconversion of alcohols and a 1dehydes/ketones, using NADH/NAD[superscript +]. Whereas the reduction reaction has been successfully reproduced in model systems with nitrogen containing ligands (including a pendant carbonyl group), no model studies published to date have investigated the role of, or included, the sulphurs. Initially, ligands containing a pyridine and two thioether groups were synthesized but these were found not to bind Zn[superscript ++] strongly enough for further study. Next, ligands containing pyridine or imidazole and two thiols were made, however the Zn[superscript ++] complexes of these precipitated from aq. solution even at low pH and no reduction, in aq. HMPA solution, of a carbonyl containing ligand of this form was found. Titrations of 1:1 complexes of these ligands (with Zn[superscript ++]) showed that at low pH's both the thiol ligands were completely deproton ated. Since these observations cast doubt on the electrophilic role of zinc in enzyme catalysis (because of charge neutralization) a new mechanism of action was proposed in which one thiol is not bound to Zn[superscript ++] in the reduction step. To counteract the effects of precipitation and charge neutralization, ligands containing a pyridine and only one thiol were prepared. However, again the required reduction could not be achieved and instead a complex reaction involving thiol and NADH analogue was seen. The second chapter deals with a new protection group for imidazole nitrogen. The N (-diethoxy methyl) group is readily introduced and the corresponding 2- lithio imidazole anion was found to react with a variety of electrophilic agents to give good yields of 2- substituted imidazoles after deprotection. Deblocking was achieved via an acidic aqueous work-up, or, if necessary, could be effected under completely neutral conditions. This method was used to make the acid-sensitive tris (4,5-diisopropylimidazol-2-yl) phosphine which had been previously shown in a preliminary study to be an effective model for CA. The third chapter deals with a detailed study of the physical properties and catalytic activity (C0[subscript 2]/HC0[subscript 3][superscript -] interconversion) of the Zn[superscript ++] and Co[superscript ++] complexes of this ligand. The catalysis was found to be first order in [Zn[superscript ++] complex] and pH dependent, the bell shaped curve obtained by plotting k[subscript cat] versus pH indicating a deficiency in Zn[superscript ++]-binding. The catalytic activity could be inhibited by halide ions in the order Cl[superscript -] >Br[superscript -] >1[superscript -] >F[superscript -] and it was proposed that the inhibitor occupied a binding site on Zn[superscript ++] to give an inactive species. The Co[superscript ++] complex was also found to be active and inhibited by Cl[superscript -]. Although no experimental support for any one reaction mechanism was found, it was noted that the presence of a protein chain (as in the active site cavity) is not a prerequisite for activity, at least in this model.
Download or read book Metalloenzymes in Denitrification written by Isabel Moura and published by Royal Society of Chemistry. This book was released on 2016-11-15 with total page 468 pages. Available in PDF, EPUB and Kindle. Book excerpt: The reduction of nitrate to nitrogen by metalloenzymes is a vital step in the nitrogen cycle. The importance of this pathway has inspired efforts to understand in greater depth the mechanisms involved. This book presents and discusses the latest information on multiple aspects of denitrification. Written by recognized specialists in the field, this book describes the bioinorganic aspects and the key enzymes involved in denitrification, including their structure, function and mechanisms. Active site modelling, novel methodologies for monitoring denitrification in vivo and biotechnological methods for water treatment are discussed. The book also focusses on the environmental implications of denitrification, such nitrate accumulation and the release of nitrous oxide into the atmosphere from excessive fertiliser use. An important topic in many biological, environmental and agricultural contexts, this book will aid teaching and help bioinorganic chemists and biotechnologists gain an up-to-date picture of the science behind the denitrification process.
Download or read book Part I Cobalt Thiolate Complexes Modeling the Active Site of Cobalt Nitrile Hydratase written by Irene Yuk Man Kung and published by . This book was released on 2002 with total page 570 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Computational Benchmarking in Biomimetic Nickel Copper and Iron Complexes written by Scott Michael Brothers and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Sophisticated catalytically active sites of metalloenzymes provide inspiration to synthetic chemists, as the metal coordination environments are often atypical to those found on the chemist's benchtop. Furthermore, metal-ligand cooperativity using earthabundant metals is anticipated to eventually supplant noble metals, currently used in industrial catalysis. Despite progress in synthesis of small molecule active site models, reproduction of the enzymatic function is rarely observed. However, differences that might define catalytic efficiency of enzymes can be addressed by theory. Density functional theory, or DFT, has been developed as an in silico tool to complement and interpret crystallographic and spectroscopic results or to make predictions in the absence of experimental data. In this dissertation, such techniques serve to elucidate the observed reactivity or electronic character of both nickel and copper bound in square planar N2S2 ligand fields, and of {Fe(NO)2} units, respectively. Nickel and copper complexes in tetraanionic N2S24− ligand environments were investigated with respect to change of metal, to modification of ligand environment, and to response in reactivity of thiolate sulfur atoms. From the DFT calculations and consistent with experimental observations, it was discovered that binding of a nucleophile at one thiolate sulfur effectively decreases reactivity of the second sulfur, and nucleophilic binding at both sulfurs serves to deactivate the complex toward further thiolate reactivity. Additionally, despite both Cu and Ni binding comfortably in the N2S24− coordination sphere, the former displays increased ionicity versus the latter, demonstrated by electrostatic potential mapping. A methodology for accurate modeling of geometry and vibrational frequencies of complexes containing a {Fe(NO)2} unit was determined from the results of a test set of complexes using a matrix of functionals and basis sets. Utilizing the optimum performer, the BP86 functional and a mixed SDD ECP basis set on iron and 6-311++G(d, p) on other atoms, a series of iron dinitrosyl complexes containing diverse ancillary ligands spanning the spectrochemical series was subsequently investigated. The electrochemical potentials of the pairs of "oxidized" and "reduced" DNIC complexes were evaluated for values occurring in the biological regime. Furthermore, as the {Fe(NO)2} unit is capable of coordination in interesting yet dissimilar geometric motifs, bimetallic, tetrameric, and adamantane-like DNIC complexes have been investigated with our DFT methodology.
Download or read book Lead Its Effects on Environment and Health written by Astrid Sigel and published by Walter de Gruyter GmbH & Co KG. This book was released on 2017-04-10 with total page 596 pages. Available in PDF, EPUB and Kindle. Book excerpt: Volume 17, entitled Lead: Its Effects on Environment and Health of the series Metal Ions in Life Sciences centers on the interrelations between biosystems and lead. The book provides an up-to-date review of the bioinorganic chemistry of this metal and its ions; it covers the biogeochemistry of lead, its use (not only as gasoline additive) and anthropogenic release into the environment, its cycling and speciation in the atmosphere, in waters, soils, and sediments, and also in mammalian organs. The analytical tools to determine and to quantify this toxic element in blood, saliva, urine, hair, etc. are described. The properties of lead(II) complexes formed with amino acids, peptides, proteins (including metallothioneins), nucleobases, nucleotides, nucleic acids, and other ligands of biological relevance are summarized for the solid state and for aqueous solutions as well. All this is important for obtaining a coherent picture on the properties of lead, its effects on plants and toxic actions on mammalian organs. This and more is treated in an authoritative and timely manner in the 16 stimulating chapters of Volume 17, which are written by 36 internationally recognized experts from 13 nations. The impact of this recently again vibrant research area is manifested in nearly 2000 references, over 50 tables and more than 100 illustrations (half in color). Lead: Its Effects on Environment and Health is an essential resource for scientists working in the wide range from material sciences, inorganic biochemistry all the way through to medicine including the clinic ... not forgetting that it also provides excellent information for teaching.
Download or read book Organometallic Chemistry written by Hiroshi Nakazawa and published by Royal Society of Chemistry. This book was released on 2021-07-19 with total page 301 pages. Available in PDF, EPUB and Kindle. Book excerpt: Designed for teaching, this book can be used as an introductory text for chemistry undergraduates and will also provide a bridge to more advanced courses.
Download or read book Concepts and Models in Bioinorganic Chemistry written by Heinz-Bernhard Kraatz and published by Wiley-VCH. This book was released on 2006-07-21 with total page 480 pages. Available in PDF, EPUB and Kindle. Book excerpt: Destined to set the standard, this book meets the need for a didactic textbook focusing on the role of model systems in bioinorganic chemistry. The first part features concepts in bioinorganic chemistry such as electron transfer, medicinal inorganic chemistry, bioorganometallics and metal DNA complexes, while the second part presents inorganic model chemistry on metallo-enzymes, organized by metal ion. Experts in the pertinent fields provide a didactically well-organized background on relevant biological systems, as well as on their structural, functional and spectroscopic properties. All chapters are similarly structured, each one beginning with a timeline featuring the most important historical facts on the subject, followed by a table of the most significant enzymes. The authors also summarize key developments and open questions within the respective model systems. This book is aimed at senior undergraduate and graduate students in chemistry, biochemistry, life science and related fields.
Download or read book NMR of Proteins and Small Biomolecules written by Guang Zhu and published by Springer Science & Business Media. This book was released on 2012-03-28 with total page 255 pages. Available in PDF, EPUB and Kindle. Book excerpt: Application of NMR and Molecular Docking in Structure-Based Drug Discovery, by Jaime L. Stark and Robert Powers NMR as a Unique Tool in Assessment and Complex Determination of Weak Protein-Protein Interactions, by Olga Vinogradova and Jun Qin The Use of Residual Dipolar Coupling in Studying Proteins by NMR, by Kang Chen und Nico Tjandra NMR Studies of Metalloproteins, by Hongyan Li and Hongzhe Sun Recent Developments in 15N NMR Relaxation Studies that Probe Protein Backbone Dynamics, by Rieko Ishima Contemporary Methods in Structure Determination of Membrane Proteins by Solution NMR, by Tabussom Qureshi and Natalie K. Goto Protein Structure Determination by Solid-State NMR, by Xin Zhao Dynamic Nuclear Polarization: New Methodology and Applications, by Kong Hung Sze, Qinglin Wu, Ho Sum Tse and Guang Zhu
Download or read book Metalloenzymes written by Claudiu T. Supuran and published by Elsevier. This book was released on 2023-08-30 with total page 636 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metalloenzymes: From Bench to Bedside offers a thorough overview of metalloenzymes, spanning biochemical and structural features, pharmacology, and biotechnological applications. After a brief overview, international experts in the field discuss a wide range of magnesium, calcium, zinc, manganese, nickel, iron, copper, cadmium, molybdenum, and tungsten enzymes, along with catalytic roles within their active sites. With a uniform approach throughout, each chapter includes the structure and function of the enzyme, physiologic and pathologic roles, inhibitors and activators of the enzyme (and their design), and clinical agents or compounds applied in medicine and drug discovery. This book enables scientists across academia and industry to adopt ongoing metalloenzyme research, and continuous discovery of novel metalloenzymes, in new life science studies and clinical applications. Examines a range of metalloenzymes, from biochemistry to pharmacology and drug design Each chapter examines enzyme structure and function, physiologic and pathologic roles, inhibitors and activators, and clinical application Features chapter contributions from international experts in the field
Download or read book Biomimetic Chemistry written by David Dolphin and published by . This book was released on 1980 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt:
