Comprehensive Coordination Chemistry II - From Biology to Nanotechnology 2 ed. in 10 Vol.Set Volume 08 - Bio-coordination Chemistry

McCleverty J.A. (ed.) Comprehensive Coordination Chemistry II - From Biology to Nanotechnology 2 ed. in 10 Vol.Set Volume 08 - Bio-coordination Chemistry 2003 [pdf 833sc 813+1c. 19.57mb] 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. Cover Page 1 Introduction to Volume 8 2 COMPREHENSIVE COORDINATION CHEMISTRY II 3 Volumes 4 Info on Volume 8 5 Volume 8 6 8.1 Recurring Structural Motifs in Bioinorganic Chemistry 6 Introduction 6 Common Motifs with Non-Amino-Acid Ligands 6 Common Motifs with Amino-Acid Ligands 11 Concluding Remarks 19 Acknowledgement 19 References 19 8.2 Electron Transfer: Cytochromes 21 Introduction 21 Heme Electronic Structure and Axial-Ligand Geometries 24 Structural Aspects of 6cLS Iron Porphyrinates 24 Out-of-plane Porphyrin Deformation 24 The Frontier Orbitals and Fe-Ligand Bonding 25 Cause and Effect Roles of Axial Ligation 27 Cytochromes c 28 Function 28 General Classifications 29 Structural Studies of Mitochondrial Cytochromes c 32 Redox-linked Conformational Changes in Class I Cytochromes c 33 Conformational Changes as a Function of pH in Class I Cytochromes c 35 Intramolecular Heme Ligand Rearrangements 38 Mitochrondrial cytochrome c folding intermediates 38 Redox-driven heme ligand switching in iso-1-cytochrome c (Phe82His) 67 Exogenous Ligand Complexes of Class I Cytochromes c 68 Exogenous ligand complexes of ferricytochromes c 68 Exogenous ligand complexes of ferrocytochrome c 69 Class II Cytochromes c` 70 Structure of cytochromes c` 70 Ligand adducts of reduced cytochromes c` 70 Folding intermediates of cytochromes c` 72 Cytochrome b562 73 Multiheme Cytochromes c 73 Cytochrome b5 74 Heme Orientation Isomers 74 Comparison of Mc and OM Cytochromes b5 75 Axial Heme Ligand Mutants of Cytochrome b5 75 Cytochrome Bc1 COMPLEX 76 Cytochrome B6f COMPLEX 76 Factors Regulating Redox Potential in Cytochromes 77 Concluding Remarks 79 References 79 8.3 Electron Transfer: Iron-Sulfur Clusters 88 Scope and Fundamental Ligand Types 88 [Fe2s2] Clusters 89 [Fe3s4] Clusters 91 Linear Clusters 91 Cuboidal Clusters 92 [Fe4s4] Clusters 94 Thiolate, Halide, and Related Clusters 94 The [Fe4S4]3+ Oxidation State 96 The [Fe4S4]1+ Oxidation State 96 Structural Trends of Fe4S4 Clusters 97 Reactions with pi-acceptor Ligands 98 Isonitrile clusters 98 Phosphine clusters 99 Fe4S4 Peptide Clusters 100 Site-differentiated Fe4S4 Clusters 101 Fe4S6 Clusters 103 Hexanuclear (Fe6s6, Fe6s8, Fe6s9) Clusters 104 Prismane (Fe6S6) Clusters 104 Basket (Fe6S6) Clusters 105 Fe6S8 Clusters 106 Fe6S9 Clusters 107 Heptanuclear (Fe7S6) and Octanuclear (Fe8S6, Fe8S8, Fe8S9, Fe8S12) Clusters 108 Fe7S6 Cluster 108 Fe8S6 Clusters 108 Fe8S8 Clusters 109 Fe8S9 Clusters 109 Fe8S12 Cluster 111 Higher Nuclearity Cyclic Clusters 111 Fe16S16 Clusters 112 Fe18S30 Clusters 112 Summary 113 References 114 8.4 Electron Transfer: Cupredoxins 118 Overview 118 Scope of the Chapter 119 The Cupredoxin Fold 119 The Colorful World of Cupredoxins and Structurally Related Proteins 119 Blue Copper Centers 121 Plastocyanin 121 Azurin 121 Other Small Blue Copper Proteins 126 Blue Copper Centers in Multidomain, Multicopper Enzymes 126 Green Copper Centers 127 Rusticyanin 127 Plantacyanin and Stellacyanin: Two Members of the Phytocyanin Family 128 Other Small Green Copper Proteins 128 Green Copper Centers in Multidomain, Multicopper Enzymes 129 Red Copper Centers 129 Purple Cua Centers 129 Cupredoxin Model Proteins 132 Mononuclear Cupredoxin Model Proteins 132 Dinuclear Cupredoxin Model Proteins 133 Cupredoxin Model Compounds 134 Mononuclear Cupredoxin Model Compounds 134 Dinuclear Cupredoxin Model Compounds 136 Summary 136 Structures 136 General features 136 The role of each structural feature in determining the spectroscopic and functional properties of cupredoxins 137 Geometry 137 Cysteine 137 Axial ligands 138 Equatorial histidines 139 Backbone carbonyl oxygen 139 Hydrogen bonding network around the primary coordination sphere 139 Spectroscopic Properties 140 Origin of the red, blue, green, and purple colors 140 Origin of the narrow copper hyperfine coupling constants 142 Electron Transfer Properties 143 Reduction potentials 143 Reorganization energy 144 Donor-acceptor electronic coupling factor 145 Acknowledgements 146 References 146 8.5 Alkali and Alkaline Earth Ion Recognition and Transport 152 Introduction 152 Physicochemical Properties that Underlie Function 153 Coordination Complexes with Proteins 154 Calcium 154 Magnesium 154 Coordination Complexes with Nucleic Acids 158 DNA 158 RNA 160 Drug-Mg2+-DNA Ternary Complexes 161 Coordination Complexes with Ion Carriers (Ionophores) 163 Coordination Chemistry of Ion Channels 165 Future Perspectives 167 References 168 8.6 Siderophores and Transferrins 170 Introduction 171 Siderophore Types 171 Catecholates 172 Hydroxamates 172 Carboxylates 173 Marine 174 Mixed Ligands 175 Siderophore Analogs 176 Solution Thermodynamics 178 Siderophore-Mediated Iron Transport 179 Gram-negative Iron Transport 180 Outer membrane 180 ATP-binding cassette (ABC) transport system 181 Periplasm 181 Cytoplasmic membrane 182 Gram-positive Transport 182 Comparison to Gram-negative iron transport 182 Cytoplasmic membrane receptors 182 Iron Regulation 183 Novel Transport Mechanisms 183 Siderophore shuttle 183 Photodecarboxylation 183 Transferrins 184 Types of Transferrins 184 Transferrins with Two Iron-binding Sites 184 Transferrins with One Iron-binding Site 185 Serum Transferrin 185 Lactoferrin 186 Ovotransferrin 186 Ferric-binding Protein 186 Melanotransferrin 186 Vertebrate Transferrin Iron-binding Sites 187 Transferrin Cycle 187 Vertebrate Transferrin Receptor Proteins 187 Mechanism of Iron Chelation and Release 189 Iron-binding residues 190 Synergistic anion 190 Dilysine trigger 191 Chelator- and anion-mediated Fe release from transferrin 191 Fe Release from Insect Transferrin 191 Bacterial Transferrin Receptor Proteins 191 Fe Release from Ferric-binding Protein in Gram-negative Bacteria 192 Conclusion 193 Acknowledgement 193 References 193 8.7 Ferritins 198 Introduction 198 General Structural And Chemical Aspects 199 Details of the Tertiary and Quaternary Protein Structure 199 A Structural Model for Loaded Ferritins 201 Current Knowledge on Structural and Physical Properties of Loaded Ferritins 202 Techniques Of Study Applied To Ferritins 203 X-ray Protein Structures 203 Features of the protein shell 203 Spectroscopic Techniques 204 Magnetic Measurements 204 Kinetic and Mechanistic Studies 205 Electron Microscopy 205 General Chemical Aspects 205 Coordination Chemistry Aspects 205 Iron(II) Uptake 205 Iron(II) Oxidation 206 Coordination chemistry of the ferroxidase centers 206 Mechanism of FeII oxidation at the ferroxidase center 206 Other studies 209 Formation of the Mineral Core: Redox Reactions and Core Formation 210 Iron(III) Storage and the Nature of the Mineral Core 213 Nature of the core and iron(III) hydrolysis 213 Methods used to probe iron core structures and their limitations 215 Diffraction experiments and electron microscopy 215 Magnetic measurements 215 Model systems 216 Iron(III) Release 220 Conclusion and Outlook 220 References 221 8.8 Metal Ion Homeostasis 224 Introduction 224 Metal Trafficking Proteins 225 Membrane Transporters 225 Atx1-like Copper Chaperones 226 Copper Chaperones for Superoxide Dismutase 227 Copper Chaperones for Cytochrome c Oxidase 228 Nickel Chaperones 229 Other Metal Co-factor Assembly Proteins 230 Metalloregulatory Proteins 230 Copper 230 Iron 232 Fur proteins 232 IdeR proteins 233 Iron-sulfur proteins 234 Zinc, Cadmium, and Mercury 234 Zur 234 ZntR and MerR 235 SmtB and CadC 235 Zinc finger proteins 237 Conclusions 237 Abbreviations 237 References 238 8.9 Metallothioneins 241 Introduction 241 Sources, Classification, and Function 242 Spectroscopic Characterization and Stoichiometry of the Metal-Sulfur Aggregates in Metallothioneins 243 Three-dimensional Structures 243 Metal Thiolates as Models of the Metal-Sulfur Aggregates in Metallothioneins 248 Dynamic Aspects and Reactivity 251 References 253 8.10 Dioxygen-binding Proteins 257 Introduction 258 The Functions of Dioxygen-binding Proteins 258 Some Properties of Dioxygen and its Reaction with Transition Metal Ions 258 Redox properties of dioxygen species 258 Types of M-O2 complexes and frontier orbital interactions 258 The O2-Carrying Proteins 259 Heme Type: Myoglobins and Hemoglobins 260 Early history and scope 260 Properties of heme and iron-porphyrins 260 Distribution and general features of myoglobins and hemoglobins 261 The heme iron-dioxygen bond 263 Mechanism of dioxygen binding 264 Binding and discrimination of CO and NO 266 Cooperativity 269 Di-iron Type: Hemerythrins and Myohemerythrins 272 Early history and distribution of hemerythrins 272 Protein structure 272 The di-iron site and formulation of the O2-binding reaction 272 Mechanism of dioxygen binding 275 Autoxidation 277 Cooperative hemerythrins 278 Mixed-valent forms 278 Synthetic models 278 Dicopper Type: Hemocyanins 279 Early history and distribution 279 Protein structure and superstructure 279 The dicopper site 279 Mechanism of dioxygen binding 281 O2-, Co-, And No-Sensing Metalloproteins 283 Types and Biological Roles 283 NO Sensing: Guanylate Cyclase and Nitrophorin 283 Regulation of Bacterial Gene Expression 284 O2 sensing: FixL and Dos 284 CO sensing: CooA 284 Bacterial Aerotaxis 285 O2 sensing: HemAT 285 O2 sensing: a hemerythrin-like protein 285 Summary 285 References 285 8.11 Heme-peroxidases 289 Introduction 289 Structures and Catalytic Activities of Selected Heme-Peroxidases 290 Horseradish Peroxidase (HRP) 290 Chloroperoxidase (CPO) 293 Ligninase (LiP) 294 Manganese Peroxidase (MnP) 296 Cytochrome c Peroxidase (CCP) 297 Peroxidasic Activity of Hemoglobin (Hb) and Myoglobin (Mb) 297 Myeloperoxidase (MPO) 298 Lactoperoxidase (LPO) 298 Thyroid Peroxidase (TPO) 298 KatG of Mycobacterium tuberculosis 299 A Short Survey of Peroxidase Models with Metalloporphyrins 299 Models of Horseradish Peroxidase 299 Models of Chloroperoxidase 300 Models of Ligninase 300 Models of Manganese Peroxidase 301 Structures and Catalytic Activities of Selected Heme-Catalases 302 Short Survey of Catalase Models with Metalloporphyrins 303 References 304 8.12 Cytochrome P450 309 Introduction 309 Metalloporphyrins as Models for Cytochrome P450 311 Early History of Metalloporphyrins 311 First-, Second-, and Third-generation Metalloporphyrins 312 Metalloporphyrins as Catalysts in Oxidation Reactions 314 Labeled Water Experiments in Oxygenation Reactions 315 High-Valent Oxoiron Porphyrins 318 Oxoiron(IV) Porphyrin Cation Radical Complexes 318 Porphyrin ligand effects 318 Axial ligand effects 319 Oxoiron(V) Porphyrins 321 Oxoiron(IV) Porphyrins 321 Mechanisms of Hydrocarbon Oxygenations 322 Multiple Oxidants in Oxygen Transfer Reactions 325 Multiple Oxidants in Cytochrome P450 Enzymes 325 Multiple Oxidants in Iron Porphyrin Models 328 Concluding Remarks 332 References 332 8.13 Nonheme Di-iron Enzymes 336 Introduction 336 Methane Monooxygenase Hydroxylase 338 Structure and Function 338 Catalytic Cycle 338 Ribonucleotide Reductase R2 Subunit 341 Structure and Function 341 Mechanism of Cofactor Assembly 342 Stearoyl-Acp Delta9 Desaturase 343 Structure and Function 343 Substrate Binding and Dioxygen Activation 343 Synthetic Model Systems 343 Carboxylate Shifts and Core Interconversion 344 Nonheme Di-iron Structural Models 344 Coordinatively saturated di(mu-carboxylato)di-iron(II) complexes 345 Carboxylate-rich di-iron(II) complexes of monodentate or bidentate N-donor ligands 347 Di-iron(II) complexes of dicarboxylate ligands XDK' 350 Di-iron(II) complexes of m-terphenyl carboxylate ligands 351 De novo protein design 352 Spectroscopic Models of Key O2 Reaction Intermediates 353 (Peroxo)di-iron(III) complexes 353 Iron(III)iron(IV) complexes: models of RNR-R2 intermediate X 358 Di-iron(IV) complexes: models of MMOH intermediate Q 360 Functional Models 360 C-H/O-H activation by well-characterized high-valent di-iron species 360 Stoichiometric and catalytic oxidation systems of biological relevance 361 Mechanisms of Dioxygen Activation 364 Summary and Outlook 365 Acknowledgements 366 References 366 8.14 Non-heme Mono-iron Enzymes 370 Catechol Dioxygenases 370 Intradiol-cleaving Catechol Dioxygenases 371 Model Systems 373 Extradiol-cleaving Catechol Dioxygenases 375 Model Systems 377 2-Oxoglutarate-Dependent Enzymes 379 Introduction 379 Structure 379 Mechanism 381 Ipns 382 Model Systems 382 Pterin-Dependent Amino Acid Hydroxylases 383 Introduction 383 Active Sites for the Amino Acid Hydroxylases 385 Mechanism for Substrate Hydroxylation 386 Lipoxygenases 387 Introduction 387 Structure 388 Mechanism 389 Model Systems 389 Arene Dioxygenases 390 Introduction 390 Structure 391 Mechanism 391 Concluding Remarks 392 References 393 8.15 Dicopper Enzymes 396 Introduction 396 Tyrosinase and Catechol Oxidase 397 Active Site Structure 397 Peroxo Intermediates: Structure and Properties 398 Enzymatic Reaction Pathways 399 Particulate Methane Monooxygenase and Ammonia Monooxygenase 402 Model Complexes of Active Oxygen Intermediates 402 Dinuclear Copper(II) Peroxo Complexes 402 Bis(mu-oxo)dicopper(III) Complexes 407 Formation Mechanisms 409 Model Reactions 410 Oxygenation of Phenols (Model Reactions for Phenolase Reaction) 410 Aliphatic C-H Bond Activation 414 Oxygen Atom Transfer Reaction 415 Concluding Remarks 416 References 416 8.16 Monocopper Oxygenases 421 Introduction 421 Monooxygenase Enzymes Containing Monocopper Active Sites 422 Dopamine beta-Monooxygenase and Peptidylglycine alpha-Hydroxylating Monooxygenase 422 Structural Models for the CuH Center: Three-coordinate Copper Complexes with All-nitrogen Ligation 425 Structural Models for the CuM Center 430 Copper complexes with mixed nitrogen/thioether ligation 430 Copper(I) aqua complexes 433 Stoichiometric C-H Monooxygenation by a Copper Biosite 433 Cofactor Biosynthesis in Copper-containing Amine Oxidases 433 Model Studies Relevant to Topaquinone Biogenesis 436 Oxidation of phenols by copper complexes 436 Hydroxylation of orthoquinones in the presence and absence of copper 438 Monocopper Oxygen Chemistry 439 Other Monocopper Dioxygen Centers in Biology 439 Copper Superoxo Complexes 440 Copper Hydroperoxo, Alkylperoxo, and Acylperoxo Complexes 444 Oxygenation of C-H Bonds Related to Copper Monooxygenase Catalysis 447 Hydroxylation of C-H Bonds &agr;- or &bgr;- to an Amine Group 447 Peptide Amidation by Metal Complexes 447 A Copper Dioxygenase Enzyme 448 Quercetinase 448 Functional Models for the Quercetinase Reaction 449 References 457 8.17 Multimetal Oxidases 463 Introduction 463 Cyctochrome c Oxidase 464 Introduction and Overview 464 X-ray Structural Studies and Physical Properties 464 Heme a and Heme a3-CuB center 465 CuA Cys-bridged binuclear center 466 Dioxygen Reduction Mechanism 466 CcO Model Compounds 467 "Blue" Copper Oxidases 470 Protein Biochemistry 470 Spectroscopy and Copper Coordination 472 X-ray Structures 472 Enzymatic O2-derived Intermediates and Reaction Mechanism 474 Native intermediate 474 Peroxide-level intermediate 475 Proposed mechanisms for O2 reduction 476 Synthetic Model Compounds 476 Models for the blue copper oxidase peroxide-level intermediate 476 Model systems involving trinuclear copper 479 References 480 8.18 Molybdenum and Tungsten Enzymes 484 Introduction 484 Perspective 484 Nature of the Catalytic Centers of Molybdenum Oxidoreductases 485 MPT 485 Classification of Molybdenum-MPT Centers 486 The DMSO Reductase Family 488 Formate Dehydrogenases 491 Dissimilatory Nitrate Reductases 492 Sulfite Oxidases 493 Xanthine Oxidases 495 Aldehyde Oxidases 496 CO Dehydrogenases 497 Nature of the Catalytic Centers of Tungsten Oxidoreductases 497 References 498 8.19 Superoxide Processing 503 The Significance Of Superoxide to Biological Utilization Of O2 503 Bio-Inorganic Models Containing O2 504 Superoxide in Biology 505 Superoxide-Generating Systems 505 NADPH Oxidase, the "Burst Oxidase" 505 Nitric Oxide Synthase (NOS) 507 Xanthine Oxidase 507 Overview of Defenses Against Superoxide 507 Cu,Zn-sod Containing Superoxide Dismutase 509 Structure 509 Mechanism and Insights from Spectroscopy 510 Fe-Containing Superoxide Dismutase 512 Structure 513 Mechanism and Insights from Spectroscopy 514 Protonation Steps Associated with Catalytic Activity 515 Mn-Containing Superoxide Dismutase 516 Structure 517 Overall Course of the Reaction 517 Mechanism and Insights from Spectroscopy 517 Protonation Steps Related to Activity, Mutation of Tyr34 or Gln146 519 Metal Ion Specificity in Fe-SOD and Mn-SOD 520 An Evolutionary Perspective 522 Ni-Containing Superoxide Dismutases 522 Structural Insights 523 Proposed Mechanism 523 Superoxide Reductases 524 Structure 525 Proposed Mechanism and Insights from Spectroscopy 525 Concluding Remarks 526 Acknowledgements 527 References 527 8.20 Oxygen Evolution 531 Introduction 532 The Photosystem II Protein Complex 532 Photochemistry of Water Oxidation 532 The Mn4 Cluster and Oxygen-Evolving Complex 533 Physical Characterization of the Oxygen-evolving Complex 533 X-ray absorption spectroscopy 534 EPR 535 Electronic absorption spectroscopy 538 Vibrational spectroscopy 539 Coordination Environment of the Mn4 Cluster 542 Amino acid ligands 542 Calcium 542 Chloride 543 H2O ligands and oxo bridges 544 Coordination Complexes as Structural and Functional Models Of the Mn4 Cluster 544 Commonly Employed Ligands 545 Structures of Oxo-bridged Manganese Complexes 545 Models with Physiologically Relevant Ligands 548 Use of Coordination Complexes to Characterize the Oxygen-evolving Complex 548 X-ray absorption spectroscopy 548 Magnetic properties 550 EPR 552 Electronic absorption spectroscopy 553 Vibrational spectroscopy 554 Electrochemical properties 554 Functional Models 555 Electron transfer in a ruthenium-linked manganese dimer 555 Catalytic oxygen evolution from a manganese dimer 556 Energetics Of Water Oxidation 557 Thermodynamics and Kinetics 558 Deuterium kinetic isotope and pH effects 558 Activation energies 558 Proton-coupled Electron Transfer 558 Proposed Mechanisms For Water Oxidation 560 Berkeley Model 560 Babcock H-atom Abstraction Model 560 Mn-oxyl Radical Model 561 Electrophilic Mn-oxo Models 562 Conclusion 564 References 566 8.21 Hydrogen Activation 572 Introduction 572 The Roles of Transition Metals in H2 Activation: A Primer of eta2-H2 Complexes and Their Reactivity 573 Electrochemical Processes: Working Hypotheses For H2 Production And Uptake Cycle 575 Coordination Spheres of Ni and Fe in the Binuclear Active Sites of [NiFe] and [Fe]H2ASES 576 Spectroscopic Studies 577 [NiFe]Hydrogenase 577 [Fe]-only Hydrogenase 578 A Comparison Of The Active Sites Of [Nife] And [Fe]H2ase 579 [NiFe]H2ASE Active-Site Model Complexes 579 [Fe]H2ase Active-Site Model Complexes 581 Fundamental Properties of FeIFeI Model Complexes 584 Activity Assay Models 584 Electrocatalytic Generation of H2 584 Theoretical Calculations Of H2 Activation 585 [Fe]-only Hydrogenase 585 [NiFe] Hydrogenase 587 Concluding Remarks 588 Acknowledgement 589 References 589 8.22 Nitrogen Fixation 592 Introduction 592 Binding of N2 to Transition Metals 593 Major Nonbiological Advances in Nitrogen Activation 594 Heterogeneous catalysis 594 Homogeneous catalysis 595 Stoichiometric N2 cleavage by coordination complexes 595 Nitrogenase 597 Metal Sites In Nitrogenase And Synthetic Model Complexes 598 Fe Protein 598 Function and structure 598 Spectroscopy 599 MoFe Protein: P Cluster 599 Function and structure 599 Spectroscopy 600 Model complexes 601 MoFe Protein: FeMo Cofactor 602 Function and structure 602 Atoms in the belt region 603 Spectroscopy 605 Extracted FeMoco 606 Model complexes 607 Interaction With Substrates 609 Dinitrogen 609 Kinetic models 609 Potential binding modes for N2 610 Molybdenum binding models 610 Iron binding models 611 Protons 613 Unnatural Substrates 613 Alternative Nitrogenases 614 Iron-Vanadium Nitrogenase 615 Iron-only Nitrogenase 615 Other Heterometal-containing Nitrogenases 616 Biosynthesis Of The Nitrogenase Cofactors 616 Conclusion 616 Acknowledgement 616 References 616 8.23 Zinc Hydrolases 623 Introduction 623 Zinc(II) Enzyme Classification By Coordinating Amino Acids 624 Progress In Understanding Mechanisms Of Zn2+-Hydrolases 624 Carboxypeptidase Family 626 Thermolysin Family 627 Astacin Superfamily 630 MMP family 630 Beta-Lactamase family 632 CA Family 633 Other Zinc(II) Hydrolases 635 Histone deacetylase (HDAC) 635 Anthrax lethal factor 635 Development Of Zn2+ Hydrolase Inhibitors 636 Carboxypeptidase Inhibitors 637 Thermolysin Inhibitors 640 MMP Inhibitors 641 Metallo beta-Lactamase Inhibitors 642 CA Inhibitors 642 HDAC Inhibitors 642 Serine Protease Inhibitors by Zinc(II) 644 Model Systems For Mononuclear Zinc(II) Enzymes 646 CA Models 646 Peptidase Models 649 Phosphatase Models 649 Beta-Lactamase Models 652 Type-II Aldolase Models 652 More Recent Developments 653 CA-mimetic zinc(II) fluorophores 653 Artificial receptors by Zn2+ enzyme models 654 Guanidine coordination to Zn2+-enzyme-model complex in aqueous solution at neutral pH 656 Summary 656 References 657 8.24 Dinuclear Hydrolases 663 Introduction 663 Hydrolases Using Divalent-Divalent Dimetal Centers 665 Urease, a Dinickel Hydrolase 665 Dizinc Hydrolases 669 Phosphotriesterase 669 Aminopeptidases 671 Metallo-beta-lactamases 675 Related systems 676 Dimanganese Hydrolases 677 Arginase 678 Related systems 679 Dicobalt Hydrolases 680 Hydrolases Using Trivalent-Divalent Dimetal Centers 681 Purple Acid Phosphatases 682 Protein Phosphatases 1, 2A, and 2B 684 Related Systems 686 Hydrolases Using Trimetal Centers 687 Alkaline Phosphatase 687 Phospholipase C 689 Inorganic Pyrophosphatase 691 Conclusions 693 References 694 8.25 Bioorganometallic Chemistry of Cobalt and Nickel 699 Introduction 699 Organocobalt Species 700 Enzymology 700 Organocobalamins: Structural Models 703 OrganocobaltIII-model Complexes 703 Methods of Synthesis of Organocobalamins and Models 704 Organocobalamins: Reactivity Models 706 Determination of Cobalt-Carbon Bond Dissociation Energies 706 Chemical Models for Specific Enzymatic Processes 708 Methionine synthases 708 Ribonucleotide triphosphate reductases 710 Cobalt participation in 1,2-migrations 711 Nickel-Containing Proteins 712 Methyl Reductase (MCR) 712 Enzymology 712 MCR: structural models 713 MeCoM and thioether binding to Ni macrocycles 714 Ni-Me models 715 MCR: reactivity models 716 Reactions of the isolated cofactor F430M 717 Methane generation from synthetic nickel complexes 717 Carbon Monoxide Dehydrogenase (COdH) 721 Enzymology 721 COdH structural models 722 COdH reactivity models 723 Acetyl Coenzyme A Synthase (ACS) 725 Enzymology 725 Structural models of the A cluster 727 ACS reactivity models 729 References 732 8.26 Metal-Radical Arrays 736 Introduction 736 CuII-Tyrosyl Radical in Galactose and Glyoxal Oxidase 737 Protein Structure and Properties 737 Synthetic Metal-phenoxyl Radical Complexes 739 Noncopper systems 740 Structures and properties of copper-phenoxyl radicals 744 Reactivity of copper-phenoxyl radicals 748 Diferric Cluster-Tyrosyl Radical In Ribonucleotide Reductase 750 Protein Structure and Properties 752 Model Complexes 752 Ferryl-Tryptophan Radical in Cytochrome C Peroxidase 753 Conclusion 754 Acknowledgement 755 References 755 8.27 Iron-Sulfur Clusters in Enzyme Catalysis 759 Introduction 759 Roles for Iron-Sulfur Clusters in Biology 759 Types of Catalytic Biological Iron-Sulfur Clusters 760 Aconitase 760 Background and Early Studies 760 The Iron-Sulfur Cluster of Aconitase 761 The Unique Iron Site 761 The Role of the Unique Iron Site in Catalysis 763 Mode of substrate binding to the unique site 763 X-ray structural studies of aconitase 763 Catalytic mechanism of aconitase 764 Aconitase and Iron Homeostasis 766 Other Hydrolytic Enzymes Containing [4Fe-4S] Clusters 767 S-Adenosylmethionine-Dependent Radical Enzymes 768 Introduction to the Radical-SAM Superfamily 768 Lysine 2,3-aminomutase 768 Pyruvate formate-lyase activating enzyme 768 Anaerobic ribonucleotide reductase activating enzyme 769 Biotin synthase and lipoate synthase 769 Spore photoproduct lyase 770 Properties of the Iron-Sulfur Clusters 770 Involvement of the Clusters in Radical Catalysis 771 Interaction of S-Adenosylmethionine with the Clusters 772 A Second Iron-Sulfur Cluster in Biotin Synthase 775 References 775 8.28 Denitrification 778 Introduction 779 Terminology 779 Biochemistry of Denitrification 779 Nitrate Reductase 779 Summary of Properties 780 Nitrite Reductase 781 Heme cd1 NiR 781 Structure 781 Mechanistic implications 783 Heme-heme electron transfer 783 Mechanistic studies 784 Model studies 786 Copper NiR 786 Structure 787 Type 1 Cu electron transfer centers 787 Type 2 Cu catalytic centers 788 Role of active site aspartate and histidine residues 788 Internal electron transfer 789 Mechanistic studies 790 Model studies 790 Bacterial Nitric Oxide Reductase 792 Prototype NOR Containing Heme c, Heme b, and Nonheme Fe 792 Structural model 793 Mechanistic studies 793 Heme-heme electron transfer 794 Substrate reduction 794 Model studies 795 Fungal P450-containing Nitric Oxide Reductase 795 Structure 797 Mechanistic Studies 798 Model Studies 799 Nitrous Oxide Reductase 800 Structure 800 Electron Transfer CuA Center 801 Catalytic CuZ Center 801 Mechanistic Implications 802 Perspective 803 References 803 8.29 DNA and RNA as Ligands 806 Introduction 807 Background: Roles of Metals in DNA and RNA Structure and Function 807 Nucleic Acids as Ligands 807 Overview of DNA/RNA Structure 807 Ligand Properties of Bases, Nucleosides, and Nucleotides 810 Ligand Properties of Oligonucleotides: Overview 811 Types of Nucleic Acid-Cation Interactions 811 Nucleic Acids are Polyelectrolytes: Counterion Condensation Theory 812 Nonspecific Site-binding 813 Specific Site-binding 814 Monovalent Ions: Group I and Thallium(I) 814 Sodium 814 Potassium, Thallium 816 Rubidium, Caesium 817 Group Iia: Magnesium/Calcium/Strontium/Barium 817 Transition Metals 818 Chromium 819 Manganese 819 Iron 820 Cobalt 820 Nickel 821 Copper 821 Zinc, Cadmium 822 Transition Metals: Second and Third Row 823 Molybdenum 823 Ruthenium 823 Silver 823 Platinum and Palladium 824 Platinum 824 Palladium 826 Tungsten, Rhenium, Gold, and Mercury 827 Tungsten, Rhenium 827 Gold 827 Mercury 827 Dimetal Complexes 828 Rh2 and Ru2 828 Mo2 828 Lead and terbium 828 References 829 8.30 Appendix to Volume 8 833 V. 1. Fundamentals : Ligands, Complexes, Synthesis, Purification, And Structure -- V. 2. Fundamentals : Physical Methods, Theoretical Analysis, And Case Studies -- V. 3. Coordination Chemistry Of The S, P, And F Metals -- V. 4. Transition Metal Groups 3-6 -- V. 5. Transition Metal Groups 7 And 8 -- V. 6. Transition Metal Groups 9-12 -- V. 7. From The Molecular To The Nanoscale : Synthesis, Structure, And Properties -- V. 8. Bio-coordination Chemistry -- V. 9. Applications Of Coordination Chemistry -- V. 10. Cumulative Subject Index. Editors-in-chief, Jon A. Mccleverty, Thomas J. Meyer. Includes Bibliographical References And Indexes.