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Publisher: Academic Press
ISBN: 9780443346477
Category : Science
Languages : en
Pages : 0
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Book Description
Mononuclear Non-heme Iron Dependent Enzymes, Volume 703 PART B focuses on methods for studying, characterizing, and leveraging the chemistry of mononuclear non-heme iron dependent enzymes. Chapters in this new release include Photoreduction for Rieske oxygenase chemistry, Insights into the Mechanisms of Rieske Oxygenases from Studying the Unproductive Activation of Dioxygen, Non-heme iron and 2-oxoglutarate enzymes catalyze cyclopropane and azacyclopropane formations, Obtaining precise metrics of substrate positioning in Fe(II)/2OG dependent enzymes using Hyperfine Sublevel Correlation Spectroscopy, Xe-pressurization studies for revealing substrate-entrance tunnels, and much more. Additional chapters cover A tale of two dehydrogenases involved in NADH recycling, Rieske oxygenases and/or their partner reductase proteins, Expression, assay and inhibition of 9-cis-epoxycarotenoid dioxygenase (NCED) from Solanum lycopersicum and Zea mays, Biocatalysis and non-heme iron enzymes, In vitro analysis of the three-component Rieske oxygenase cumene dioxygenase from Pseudomonas fluorescens IP01, Structure and function of carbazole 1,9a-dioxygenase, Characterization of a Mononuclear Nonheme Iron-dependent Mono-oxygenase OzmD in Oxazinomycin Biosynthesis, and much more.
Author:
Publisher: Academic Press
ISBN: 9780443346477
Category : Science
Languages : en
Pages : 0
Get Book Here
Book Description
Mononuclear Non-heme Iron Dependent Enzymes, Volume 703 PART B focuses on methods for studying, characterizing, and leveraging the chemistry of mononuclear non-heme iron dependent enzymes. Chapters in this new release include Photoreduction for Rieske oxygenase chemistry, Insights into the Mechanisms of Rieske Oxygenases from Studying the Unproductive Activation of Dioxygen, Non-heme iron and 2-oxoglutarate enzymes catalyze cyclopropane and azacyclopropane formations, Obtaining precise metrics of substrate positioning in Fe(II)/2OG dependent enzymes using Hyperfine Sublevel Correlation Spectroscopy, Xe-pressurization studies for revealing substrate-entrance tunnels, and much more. Additional chapters cover A tale of two dehydrogenases involved in NADH recycling, Rieske oxygenases and/or their partner reductase proteins, Expression, assay and inhibition of 9-cis-epoxycarotenoid dioxygenase (NCED) from Solanum lycopersicum and Zea mays, Biocatalysis and non-heme iron enzymes, In vitro analysis of the three-component Rieske oxygenase cumene dioxygenase from Pseudomonas fluorescens IP01, Structure and function of carbazole 1,9a-dioxygenase, Characterization of a Mononuclear Nonheme Iron-dependent Mono-oxygenase OzmD in Oxazinomycin Biosynthesis, and much more.
Author:
Publisher: Elsevier
ISBN: 0443313059
Category : Science
Languages : en
Pages : 348
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Book Description
Mononuclear Non-heme Iron Dependent Enzymes, Volume 703 focuses on methods for studying, characterizing, and leveraging the chemistry of mononuclear non-heme iron dependent enzymes. Chapters in this new release include Photoreduction for Rieske oxygenase chemistry, Insights into the Mechanisms of Rieske Oxygenases from Studying the Unproductive Activation of Dioxygen, Non-heme iron and 2-oxoglutarate enzymes catalyze cyclopropane and azacyclopropane formations, Obtaining precise metrics of substrate positioning in Fe(II)/2OG dependent enzymes using Hyperfine Sublevel Correlation Spectroscopy, Xe-pressurization studies for revealing substrate-entrance tunnels, and much more. Additional chapters cover A tale of two dehydrogenases involved in NADH recycling, Rieske oxygenases and/or their partner reductase proteins, Expression, assay and inhibition of 9-cis-epoxycarotenoid dioxygenase (NCED) from Solanum lycopersicum and Zea mays, Biocatalysis and non-heme iron enzymes, In vitro analysis of the three-component Rieske oxygenase cumene dioxygenase from Pseudomonas fluorescens IP01, Structure and function of carbazole 1,9a-dioxygenase, Characterization of a Mononuclear Nonheme Iron-dependent Mono-oxygenase OzmD in Oxazinomycin Biosynthesis, and much more. Provides detailed articles regarding how to study the structures and mechanisms of mononuclear non-heme iron dependent enzymes Guides readers on how to use partner proteins in non-heme iron enzyme catalysis Includes strategies to employ mononuclear non-heme iron enzymes in biocatalytic applications
Author: Sam P. De Visser
Publisher: Royal Society of Chemistry
ISBN: 1849731810
Category : Science
Languages : en
Pages : 463
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Book Description
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.
Author: Yu-Min Catherine Chiou
Publisher:
ISBN:
Category :
Languages : en
Pages : 534
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Book Description
Author: Kenneth M. Light
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Mononuclear nonheme iron enzymes (NH Fe enzymes) catalyze a variety of biological reactions. A large group of NH Fe enzymes use a ferrous active site to activate dioxygen towards reaction with substrate, and require an additional cofactor as a source of electrons necessary for catalysis. The main part of this thesis involves the application of a circular dichroism (CD), magnetic circular dichroism (MCD) and variable temperature, variable-field MCD (VTVH MCD) spectroscopic methodology to a series of alpha-ketoglurate-dependent (alpha-KG-dependent) enzymes for the purpose of understanding how this enzyme family and the NH Ferrous enzymes in general induce the dissociation the generation of a 5C site for dioxgyen reactivity, as well as how dioxygen binding is oriented for proper catalysis. In addition to catalyzing oxidation of organic substrates, NH Fe enzymes are also involved in the catalytic hydrolysis and hydration of substrates. A prominent example of this is nitrile hydratases (NHases), unusual low-spin (LS) Ferric or Cobaltic enzymes that catalyze the conversion of nitriles to amides in soil bacteria. Another part of this thesis involves the spectroscopic characterization of a ferric NHase for the determination of its active site geometric and electronic structure, which are used to calibrate a computational model which is extended to explore the NHase catalytic mechanism.
Author: Christopher J Schofield
Publisher: Royal Society of Chemistry
ISBN: 1849739501
Category : Science
Languages : en
Pages : 508
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Book Description
Since the discovery of the first examples of 2-oxoglutarate-dependent oxygenase-catalysed reactions in the 1960s, a remarkably broad diversity of alternate reactions and substrates has been revealed, and extensive advances have been achieved in our understanding of the structures and catalytic mechanisms. These enzymes are important agrochemical targets and are being pursued as therapeutic targets for a wide range of diseases including cancer and anemia. This book provides a central source of information that summarizes the key features of the essential group of 2-oxoglutarate-dependent dioxygenases and related enzymes. Given the numerous recent advances and biomedical interest in the field, this book aims to unite the latest research for those already working in the field as well as to provide an introduction for those newly approaching the topic, and for those interested in translating the basic science into medicinal and agricultural benefits. The book begins with four broad chapters that highlight critical aspects, including an overview of possible catalytic reactions, structures and mechanisms. The following seventeen chapters focus on carefully selected topics, each written by leading experts in the area. Readers will find explanations of rapidly evolving research, from the chemistry of isopenicillin N synthase to the oxidation mechanism of 5-methylcytosine in DNA by ten-eleven-translocase oxygenases.
Author: Shyam Rajan Iyer
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Author: Shaun Di Hang Wong
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Mononuclear non-heme iron (NHFe) enzymes catalyze a wide variety of biologically-important reactions such as hydroxylation, halogenation, desaturation, ring closure, and electrophilic aromatic substitution. The key intermediate in the catalytic cycle is the S = 2 Fe(IV)=O species, capable of abstracting an H-atom from inert C--H bonds as strong as 106 kcal/mol. The Fe(IV)=O intermediate in enzymes is transient and difficult to trap; as such, stable synthetic analogs have proven invaluable for spectroscopic elucidation of the geometric/electronic structure of the Fe(IV)=O unit and how it is activated for reactivity. Such biomimetic Fe(IV)=O model complexes can be either intermediate-spin (S = 1) or high-spin (S = 2) in contrast to the S = 2 ground state of enzyme intermediates. For an S = 1 Fe(IV)=O species, the Fe--oxo [beta] [pi]*-frontier molecular orbital (FMO) [from the combination of Fe d(xz/yz) and oxo p(x/y)] is involved in H-atom abstraction, and this FMO requires a side-on approach ([pi]-attack) to achieve maximum overlap with the substrate C--H bond. Through magnetic circular dichroism (MCD) and nuclear vibrational resonance spectroscopy (NRVS) studies, the reactivity of the S = 1 Fe(IV)=O unit has been shown to be affected by the oxo contribution in the [pi]*-FMO, where a larger oxo contribution results in greater orbital overlap (with the substrate C--H) and higher reactivity; also, the [pi]-attack pathway results in steric clashes between substrate and ligand, giving a significant steric contribution to the energy of the reaction barrier. For an S = 2 Fe(IV)=O species, the Fe--oxo [alpha] [sigma]*-FMO [Fe d(z2) and oxo p(z)] is spin-polarized (exchange-stabilized) to an energy level comparable with its [pi]*-FMO, making it accessible as a second pathway ([sigma]-attack) for reactivity. In the S = 2 Fe(IV)=O model complex ligated by TMG3tren, this [sigma]*-FMO is active but is axially hindered by the ligand, again giving a large steric contribution to the reaction barrier; however, the intrinsic electronic reaction barriers of the S = 2 [sigma]*-FMO and the S = 1 [pi]*-FMO are comparable, suggesting they are similarly active in H-atom abstraction. Furthermore, MCD excited-state spectroscopy in combination with multiconfigurational calculations on the S = 2 model reveal two different [pi]-pathways for reactivity involving Fe(III)--oxyl[p(x), [pi]] character, in addition to the [sigma]-pathway involving Fe(III)--oxyl[p(z), [sigma]] character, showing that the S = 2 Fe(IV)=O unit is activated for both [pi] and [sigma] H-atom abstraction reactivities. Finally, the S = 2 enzyme intermediate for the halogenase SyrB2 was trapped and structurally characterized by NRVS, revealing two possible 5-coordinate trigonal bipyramidal candidates with the Fe--oxo vector oriented either perpendicular or parallel to the substrate C--H bond. Importantly, this difference in orientation leads to Fe(III)--OH products oriented efficiently for different rebound reactivities -- native halogenation in the case of perpendicular orientation and non-native hydroxylation in the case of parallel orientation.
Author: Adrienne Renee Diebold
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Mononuclear non-heme iron enzymes are an important class with a wide range of medical, pharmaceutical and environmental applications. Within this class, the oxygen activating enzymes use Fe(II) to activate O2 for reaction with the substrate. The focus of this thesis is on understanding two major themes of the oxygen activating enzymes - the role of the (2His/1 carboxylate) facial triad and the initial O2 reaction steps of alpha-keto acid-dependent dioxygenases - using a combination of spectroscopic techniques and DFT calculations. For ferrous systems, abs/CD/MCD/VTVH MCD studies define the geometric and electronic structure of the ferrous site. In combination with DFT calculations, a structure/function picture of the ferrous sites is developed. To extend these studies to the initial steps of O2 binding, studies with NO as an O2 analogue ({FeNO}7/{FeO2}8) utilize EPR/abs/CD/MCD/VTVH MCD spectroscopy with DFT calculations to elucidate important effects of the substrate on the {FeNO}7 bond. These effects are used in the computational extension to the experimentally inaccessible O2 bound complexes giving insight into the initial steps of O2 binding and activation. Taken together, these studies shed light on the rational for facial triad ligation at the Fe(II) site in the oxygen activating enzymes and how the Fe(II) ligand set tunes the specific reactivity of these enzymes.
Author: Paul C. Tarves
Publisher:
ISBN:
Category :
Languages : en
Pages : 468
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Book Description
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.
