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Book Details
Abstract
There has been enormous progress in our understanding of molybdenum and tungsten enzymes and relevant inorganic complexes of molybdenum and tungsten over the past twenty years. This set of three books provides a timely and comprehensive overview of the field and documents the latest research.
Building on the first volume that focussed on biochemistry aspects, the second volume in the set focusses on the inorganic complexes that model the structures and reactivity of the active sites of each major group of molybdenum and tungsten enzymes. Special attention is given to synthetic strategies, reaction mechanism and chemical kinetics of these systems. The introductory chapter provides a useful overview and places the topic of the book into a wider context.
This text will be a valuable reference to workers both inside and outside the field, including graduate students and young investigators interested in developing new research programs in this area.
This book is edited by Professor Russ Hille (University of California, Riverside), Professor Carola Schulzke (University of Greifswald) and Professor Martin Kirk (University of New Mexico) who have over 275 publications ad over 65 years of experience between them in the field. Their complementary expertise in molybdenum containing enzymes, bioinorganic chemistry and the physical inorganic chemistry of molybdenum complexes and enzymes, respectively, allow the authoritative and comprehensive coverage demonstrated in this book.
Table of Contents
| Section Title | Page | Action | Price |
|---|---|---|---|
| Cover | Cover | ||
| Molybdenum and Tungsten Enzymes Bioinorganic Chemistry | i | ||
| Preface | v | ||
| Dedication | vii | ||
| Contents | ix | ||
| Chapter 1 - An Overview of the Synthetic Strategies, Reaction Mechanisms and Kinetics of Model Compounds Relevant to Molybdenum- and Tungsten-Containing Enzymes | 1 | ||
| Introduction and Overview | 1 | ||
| Chapter 2 - Pterin-Inspired Model Compounds of Molybdenum Enzymes | 8 | ||
| 2.1 Introduction | 8 | ||
| 2.2 Unveiling the Pterin Component of Moco | 10 | ||
| 2.2.1 The Pterin is Discovered | 10 | ||
| 2.3 Development of Pterin-Inspired Models | 15 | ||
| 2.3.1 First-Generation Models | 15 | ||
| 2.3.1.1 Models Where Molybdenum is Coordinated Directly to Pterins | 15 | ||
| 2.3.1.2 Model Exploration of Redox Processes Between Mo and Pterin | 18 | ||
| 2.3.1.2.1\rPterin Redox Chemistry.Participation in redox processes is one of the fundamental roles of pteridines in biology, and pterins mo... | 18 | ||
| 2.3.1.2.2\rPterin-Molybdenum Redox Chemistry.The early studies focused on Mo(vi) and tetrahydropterin reagents to closely mimic the Mo and ... | 20 | ||
| 2.3.1.2.3\rReactivity of Molybdenum Complexes of Reduced Pterins.To reconcile the contradictory Mo and pterin oxidation state assignments, ... | 23 | ||
| 2.3.1.2.4\rDMSO Reduction.Model compounds for the molybdenum cofactor are often developed to be capable of mimicking biological activity.2c... | 24 | ||
| 2.3.1.2.5\rMolybdenum(iv) Reactions with Oxidized Pterins.Long before a pteridine was discovered in Moco, the reaction of Mo(iv) and flavin... | 27 | ||
| 2.3.1.2.6\rFormal Oxidation States in Molybdenum–Pterin Complexes.These molybdenum–pterin complexes share a theme: all complexes provide ev... | 30 | ||
| 2.3.1.2.7\rEvidence for the Non-innocent Nature of Pterin Ligands.The sum of experimental and computational results emphasizes that the ele... | 32 | ||
| 2.3.2 Second-Generation Dithiolene Pterins and their Complexes | 33 | ||
| 2.3.2.1 Synthesis of Mo-Dithiolene Complexes in Reactions of Alkynes and Metal Polysulfides | 34 | ||
| 2.3.2.2 Synthesis of Dithiolene Ligands and Complexes from Protected Dithiolene Precursors | 36 | ||
| 2.3.2.3 Synthesis of Sulfur-Containing Pterin Molecules | 42 | ||
| 2.3.2.3.1\rChemical Synthesis of the Moco Metabolite Urothione.In 1982, Johnson and Rajagopalan published10 their seminal paper proposing t... | 42 | ||
| 2.3.2.3.2\rSynthesis of Pterin Dithiolene Ligand.In 1971, Hartzler communicated that an ylide can be formed by reacting an activated alkyne... | 43 | ||
| 2.3.3 Third-Generation Dithiolene Pterins and their Complexes | 43 | ||
| 2.3.3.1 A Route to a Synthetic Pyranopterin Leads to Molybdopterin in Protected Form | 44 | ||
| 2.3.3.2 A Retrosynthetic Analysis Approach | 47 | ||
| 2.3.3.3 Spontaneous Pyran Ring Cyclization Within a Pterin Dithiolene Complex | 48 | ||
| 2.3.3.4 Determining the Redox State of the Pyranopterin System | 49 | ||
| 2.3.4 Chemical Behavior of Dithiolenes Substituted by Pterin and N-Heterocycles | 53 | ||
| 2.4 Unresolved Questions and Current Objectives | 57 | ||
| Acknowledgement | 59 | ||
| References | 59 | ||
| Chapter 3 - Electron Transfer Mechanisms in Molybdenum and Tungsten Model Compounds | 68 | ||
| 3.1 Introduction to Molybdenum and Tungsten | 68 | ||
| 3.1.1 Role in Biology | 69 | ||
| 3.2 Model Systems | 70 | ||
| 3.3 Electron Transfer in Molybdoenzymes | 78 | ||
| 3.3.1 Principle Involved in Electron Transfer Reactions | 80 | ||
| 3.4 Conclusion | 87 | ||
| References | 88 | ||
| Chapter 4 - Comparative Kinetics of Enzymes and Models | 94 | ||
| 4.1 Active Sites of Molybdenum and Tungsten Enzymes | 94 | ||
| 4.2 General Remarks on Michaelis–Menten Kinetics | 96 | ||
| 4.2.1 Determination of Michaelis–Menten Parameters | 100 | ||
| 4.2.2 Michaelis–Menten Kinetics for Oxygen Transfer Reactions – “Quo Vadis” | 103 | ||
| 4.3 Kinetic Aspects of Oxygen Transfer Reactions – Enzymes vs. Models | 106 | ||
| 4.3.1 Oxygen Transfer Reactions Mediated by Enzymes | 106 | ||
| 4.3.2 Studying Half-Reactions of Model Complexes | 107 | ||
| 4.3.3 Selected Historical Steps in Functional Model Development | 116 | ||
| 4.3.4 Half-Reaction Kinetics Applied to a Two-Substrate Catalytic Cycle – A Simulation | 121 | ||
| 4.4 Dedication and Acknowledgements | 124 | ||
| References | 125 | ||
| Chapter 5 - Synthetic Models of the Nitrogenase Clusters | 130 | ||
| 5.1 Introduction | 130 | ||
| 5.2 The Nitrogenase Metalloclusters: A Synthetic Perspective | 131 | ||
| 5.2.1 The F-Cluster | 132 | ||
| 5.2.2 The P-Cluster | 132 | ||
| 5.2.3 The FeMo-Cofactor | 133 | ||
| 5.3 Synthetic Considerations | 134 | ||
| 5.4 F-Cluster Analogues: The All-Ferrous State | 136 | ||
| 5.5 Modeling the Nitrogenase Superclusters | 137 | ||
| 5.5.1 Heterometallic Cores | 137 | ||
| 5.5.2 Topological Analogues | 141 | ||
| 5.5.2.1 Higher Nuclearities and Sulfur-Voided Cubanes | 141 | ||
| 5.5.2.2 All-Sulfide PN-Type Cores | 144 | ||
| 5.5.2.3 Neutral Octanuclear Clusters | 146 | ||
| 5.5.3 Heteroligated Cores | 148 | ||
| 5.5.3.1 Oxide–Sulfide Cores | 150 | ||
| 5.5.3.2 Imide–Sulfide Cores | 151 | ||
| 5.6 Cluster Assembly Mechanisms: Chalcogen-Labeled Cores | 154 | ||
| 5.7 Status and Prospects | 158 | ||
| Abbreviations | 158 | ||
| Acknowledgements | 159 | ||
| References | 159 | ||
| Chapter 6 - Synthesis of Mono- and Bisdithiolene Molybdenum and Tungsten Model Compounds | 166 | ||
| 6.1 Introduction | 166 | ||
| 6.2 Model Compounds for the DMSOR Family | 169 | ||
| 6.2.1 The MoVIO2 and MoIVO Couple | 170 | ||
| 6.2.2 The MoVIO and MoIV Couple | 176 | ||
| 6.2.3 MoVIS(Se-R) and MoIVS Couple | 181 | ||
| 6.3 Model Compounds for the Sulfite Oxidase Family | 182 | ||
| 6.4 Model Compounds for the Xanthine Oxidase Family | 183 | ||
| 6.5 W-substituted Model Compounds for the DMSOR and Xanthine Oxidase Families | 185 | ||
| 6.6 Model Compounds for Tungsten-Dependent Enzymes | 186 | ||
| 6.6.1 The WVIO(S) Center | 186 | ||
| 6.6.2 The WVIS(Se-R) Center | 188 | ||
| 6.6.3 The WVI(CO/CN)(SR) Center | 189 | ||
| 6.6.4 The Unidentified W Center | 189 | ||
| 6.7 Conclusion | 190 | ||
| References | 190 | ||
| Chapter 7 - Models for the Xanthine Oxidase Family of Enzymes | 194 | ||
| 7.1 Introduction | 194 | ||
| 7.2 Molybdenum Hydroxylases | 195 | ||
| 7.2.1 Overview of the Enzymes | 195 | ||
| 7.2.2 Key Discoveries Informing Model Studies | 196 | ||
| 7.2.3 Active Sites and Model Targets | 199 | ||
| 7.3 Active Site Components: Synthetic Background | 200 | ||
| 7.3.1 General Challenges | 200 | ||
| 7.3.2 The Chalcogenido Components: Background, Synthetic Approaches and Reagents | 201 | ||
| 7.3.2.1 Oxosulfido- and Oxoselenido-Mo(vi) Species | 201 | ||
| 7.3.2.1.1\rSynthetic Strategy 1: Oxo to Sulfido/Selenido Ligand Conversions.The OSCR is a conceptually simple strategy for the synthesis of... | 202 | ||
| 7.3.2.1.2\rSynthetic Strategy 2: Atom Transfer Methodologies.Bidirectional OAT reactions capable of inter-converting dioxo-Mo(vi) and oxo-M... | 204 | ||
| 7.3.2.2 Hydrosulfido-Mo Species | 206 | ||
| 7.3.2.3 µ-Sulfido Bridged Oxo–Mo–Cu Complexes | 206 | ||
| 7.3.3 The Mono(dithiolene) Component: Background and Synthetic Approaches | 207 | ||
| 7.3.3.1 Dithiolene Complexes | 207 | ||
| 7.3.3.2 Strategies for the Synthesis of Mono(dithiolene) Complexes | 208 | ||
| 7.3.4 Maintaining Mononuclearity Post-Synthesis | 209 | ||
| 7.4 Molybdenum Hydroxylase Models | 211 | ||
| 7.4.1 Models of Enzymes Containing Oxosulfido and Oxoselenido Active Sites | 211 | ||
| 7.4.1.1 Models of Oxidized Enzymes | 211 | ||
| 7.4.1.1.1\rThiomolybdates.Thiomolybdates are included in our discussion not because they are MoHMs per se but because they are historically... | 211 | ||
| 7.4.1.1.2\rPseudo-Tetrahedral Oxosulfido-Mo(vi) Complexes.The first mono | 212 | ||
| 7.4.1.1.3\rOxosulfido-Mo(vi) Scorpionate Complexes.Scorpionate lig | 213 | ||
| 7.4.1.1.4\rOther Oxosulfido-Mo(vi) Hard-Donor Complexes.The first octahedral, oxosulfido-Mo(vi) complexes to contain an “unperturbed” termi... | 217 | ||
| 7.4.1.1.5\rDithiolene Complexes.Currently, there are no models combining the oxosulfido-Mo(vi) and mono(dithiolene) components of Mo hydrox... | 218 | ||
| 7.4.1.2 Models of Reduced Enzymes | 219 | ||
| 7.4.1.2.1\rOxosulfido- and Oxo(hydrosulfido)-Mo(v) Compounds.Only a handful of mononuclear, EPR-active oxosulfido- and oxo(hydrosulfido)-Mo... | 219 | ||
| 7.4.1.2.2\rOxo(hydrosulfido)-Mo(iv) Complexes.The reactions of NBun4 | 222 | ||
| 7.4.2 Models for the MoO(µ-S)Cu Active Site of CODH | 223 | ||
| 7.4.2.1 Oxo-di-µ-sulfido-MoVICuI Dithiolene Complexes | 223 | ||
| 7.4.2.2 Oxo-µ-Sulfido-MoVCuI Scorpionate Complexes | 224 | ||
| 7.5 Conclusion | 226 | ||
| Dedication and Acknowledgements | 227 | ||
| References | 228 | ||
| Subject Index | 239 |