Download or read book Synthesis and Characterization of Nickel Complexes with Relevance to Nickel Acireductone Dioxygenase and Nickel Superoxide Dismutase written by Margo Nicole Montgomery and published by . This book was released on 2012 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research presents an investigation of synthetic model complexes with relevance to the active site of Ni(II) acireductone dioxygenase (Ni-ARD) and Ni(II) superoxide dismutase (Ni-SOD). Acireductone dioxygenases (ARDs) are a unique set of enzymes found in the methionine salvage pathway that catalyze the oxidation reaction of acireductone (1, 2-dihydroxy-3-oxo-5-(methylthio)pent-1-ene). These enzymes share a common polypeptide sequence but bind different metal ions, Ni 2+ or Fe2+, at the active site. The Ni-ARD enzyme is responsible for the off pathway shunt in the pathway. Using the tridentate nitrogen donor ligands hydrotris(3,5-dimethyl-1-pyrazolyl)borate (Tp*) and the newly developed tris(1, 2-dimethyl-4-imadozyl)carbinol, (4-TIC Me, Me) several reactions involving the acireductone analog 2-hydroxy-1, 3-diphenylpropan-1, 3-dione and O2 were investigated for similarities to the Ni-ARD active site. Superoxide dismutases (SODs) play a key role in protecting cells against oxidative damage by regulating the cellular concentration of the superoxide radical (O2.- ) which is an unwanted byproduct of cellular metabolism. This process is accomplished by converting the superoxide radicals to hydrogen peroxide and molecular oxygen. Several small-molecule complexes were synthesized and characterized in an effort to model the reduced state of the Ni-SOD using the Tp* ligand. The structures for these complexes have been determined using X-Ray Crystallography.
Download or read book Synthesis and Characterization of Nickel Imine amine Complexes a Possible Model for Nickel Superoxide Dismutase written by Tom Muinde Mwania and published by . This book was released on 2012 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: Superoxide dismutases are ubiquitous enzymes that efficiently catalyze the disproportionation of superoxide radical anions to protect biological molecules from oxidative damage. Several SODs have been identified having different metals at their active sites. These include Mn SOD, Fe SOD, Cu/Zn SOD and, most recently, Ni SOD. The catalytic center of Ni SOD resides in the N-terminal active-site loop, where a Ni(II) is coordinated by the amine N of His-1, the amide N of Cys-2, and two thiolate S atoms of Cys-2 and Cys-6. In the oxidized form, Ni(III) adds the imidazole N of His-1 as an axial ligand. For the past decade, we have been developing methodology using 2, 2'-dithiodibenzaldehyde (DTDB) for the synthesis of metal complexes with mixed N/S coordination. We are reporting on the application of this methodology to the synthesis of model complexes for the active site of NiSOD, in which we have successfully synthesized and characterized three NiIIN2S2 complexes of imine/amine N donors: Ni(NNS)SPh (1), Ni(NNS)SPhNO2 (2) and Ni(NNS)StBu (3). These may be used as a model for reduced NiSOD, with future plans of comparing to complexes with amide/amine N donors, thus establishing the role of the amide.
Download or read book Synthesis and Characterization of a Model Nickel Superoxide Dismutase Metallopeptide Functionalized for Hydrogen Production written by Bevan Griffith Meade and published by . This book was released on 2014 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Organic Chemistry of Nickel written by P.W. Jolly and published by Elsevier. This book was released on 2012-12-02 with total page 417 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Organic Chemistry of Nickel, Volume II: Organic Synthesis describes the chemistry of the organonickel complexes and the use of nickel in organic synthesis. Composed of six chapters, this volume starts with discussions on the oligomerization, co-oligomerization, and polymerization of olefins, followed by short accounts of the mechanistically related isomerization and hydrogenation of olefins, as well as the hydrosilylation and hydrocyanation reactions. Chapter II examines the oligomerization of acetylene and substituted alkynes, the co-oligomerization of alkynes with olefins, the related oligomerization of allene, including a number of telomerization reactions involving alkynes or allenes. Chapters III and IV describe the oligomerization, co-oligomerization, and polymerization of butadiene and substituted 1,3-dienes. Chapter V explores the coupling of organic halides in the presence of stoichiometric amounts of zerovalent nickel complexes, and the nickel-catalyzed cross-coupling reaction between organic halides and Grignard reagents. Lastly, Chapter VI emphasizes the carbonylation of alkynes, olefins, and organic halides using nickel complexes. This book will be of great value to organic chemists and researchers who are interested in the application of nickel complexes to organic synthesis.
Download or read book Bioinorganic Chemistry of Nickel written by Michael J. Maroney and published by MDPI. This book was released on 2020-06-16 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: The chemistry of nickel in biological systems has been intensely investigated since the discovery of the essential role played by this transition metal in the enzyme urease, ca. 1975. Since then, several nickel-dependent enzymes have been discovered and characterized at the molecular level using structural, spectroscopic, and kinetic methods, and insight into reaction mechanisms has been elaborated using synthetic and computational models. The dual role of nickel as both an essential nutrient and as a toxin has prompted efforts to understand the molecular mechanisms of nickel toxicology and to uncover the means by which cells select nickel from among a pool of different and more readily available metal ions and thus regulate the intracellular chemistry of nickel. This latter effort highlights the importance of proteins involved in the extra- and intra-cellular sensing of nickel, the roles of nickel-selective proteins for import and export, and nickel-responsive transcription factors, all of which are important for regulating nickel homeostasis. In this Special Issue, the contributing authors have covered recent advances in many of these aspects of nickel biochemistry, including toxicology, bacterial pathogenesis, carcinogenesis, computational and synthetic models, nickel trafficking proteins, and enzymology.
Download or read book Synthesis and Characterization of Nickel II Complexes of a Hydrotrispyrazolylborato Ligand and of the Thiosalicylato Ligand written by Weibin Chen and published by . This book was released on 1994 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis and Characterization of Nickel II Complexes with 1 4 7 10 tetrabenzyl 1 4 7 10 tetraazacyclododecane written by George A. Kalligeros and published by . This book was released on 1971 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis and Characterization of Nickel thiolate Complexes as a Model of the Active Site of Ni Fe Hydrogenase Enzymes written by Dao Hinh Nguyen and published by . This book was released on 1997 with total page 708 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Design Synthesis and Properties of Nickel Complexes that Replicate the Structural and Electronic Properties of the N3S2 Donor Set of Ni Containing Superoxide Dismutase written by Phan T. Truong and published by . This book was released on 2018 with total page 686 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nickel superoxide dismutase (NiSOD) is a metalloenzyme that can catalyze the disproportionation of superoxide (O2") to O2 and H2O2 at the diffusion-controlled rates. In the NiSOD active site, the Ni ion is situated in a mixed amine/peptide thiolates N3S2 coordination environment. The unique NiSOD active site promotes facile Ni(III/II) redox while prevents the oxidation/oxygenation of thiolates by the substrate and products of O2" disproportionation. This has prompted the development of relatively small synthetic analogues of NiSOD by our group and others to understand the role of mixed N/S donors in NiSOD. We reported the first five-coordinate (5C) analogue, K[Ni(N3S2)] (1), that replicates the N3S2 donor set of NiSOD structurally and electronically with a pendant pyridine as potential fifth ligand to Ni in the axial position. However, oxidation of 1 by ferrocenium hexafluorophosphate (FcPF6) yielded a disulfide-bridged complex. The increased in basicity as well as steric enforcement by incorporation of gem-(CH3)2 moiety in the second-generation analogue, Na[Ni(N3S2Me2)] (2), is expected to promote Ni-based redox while preventing disulfide formation at the S trans to carboxamide. However, the increase in steric enforcement in 2 led to a new oxidation pathway that yielded a thiazolidine ring rearrangement product that was not observed in 1. Since coordination of axial N-ligand to Ni is critical in promoting Ni-based redox in NiSOD, the pendant pyridine is replaced with N-ethylmorpholine (NEM) moiety in the third-generation analogue, Na[Ni(N3S2NEM)] (3). The more Lewis basic N-donor in 3 is expected to coordinate to both Ni2+ and Ni3+ oxidation state to promote Ni-based redox. Reactions of 3 with oxidants (air, FcPF6, and KO2) and Lewis acid (i.e. tris(pentafluorophenyl) borane) yielded stair-step trimetallic species with N-NEM poised to coordinate to terminal [NiN3S2] centers. CV of these trimetallic species exhibited multiple reversible redox couples assigned to the terminal [NiN3S2] centers. These results show that while 1-3 can replicate NiSOD active site electronically and structurally, reversible Ni(III/II) redox couple is not achievable unless the electron density on S-thiolates is sequestered by Lewis acids (i.e., Ni2+ and borane), which mimics the H-bond interactions in NiSOD active site.
Download or read book Synthesis and Characterization of Nickel II Complexes of a Hydrotrispyrazolylborate Ligand and of Novel Phosphinetrithiol Ligands written by Weihong Zhang and published by . This book was released on 1990 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis and Characterization of Nickel III Thiolate Complexes for O H and C H Bonds Activation written by and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Chemistry of NI II Complexes of Relevance to Acireductone Dioxygenase written by Ewa Szajna-Fuller and published by . This book was released on 2006 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Schiff Base based nickel complexes as precursors for chemical vapour deposition CVD Process Designing synthesis characterization and thermo gravimetric TG DTA evaluation written by Dr. S. Arockiasamy and published by Book Rivers. This book was released on 2023-11-17 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis and Characterization of Nickel II Compounds with Sulfur Donor Ligands written by Li Zhou and published by . This book was released on 1995 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Model Complexes for Nickel Containing Enzymes written by Joshua Robert Zimmerman and published by . This book was released on 2009 with total page 209 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon Monoxide Dehydrogenase / Acetyl CoA Synthase (CODH/ACS) is a bifunctional enzyme that catalyzes the reduction of CO2́2 to CO and the assembly of Acetyl CoA. The A-cluster active site, which catalyzes the Acetyl CoA synthesis, contains a Fe-S cubane bridged by a cysteine thiolate to a dinuclear Ni(℗æ-S)2́2Ni cluster (Fig. 1). The proximal nickel, Nip, has S2́3X coordination, while the distal nickel, Nid, has N2́2S2́2 coordination. This project focuses on the synthesis of model complexes for the asymmetric dinuclear metal center in order to understand the electronic characteristics of this cluster and investigate the feasibility of proposed intermediates. The initial target compound is shown in Figure 2. We have developed an efficient method for synthesizing metal complexes with mixed N/S coordination through the use of 2-2'-dithiodibenzaldehyde, DTDB. Symmetric nickel complexes with NS2́3 coordination have previously been synthesized using DTDB and various bidentate NS ligands. Herein we present our results upon incorporating N,N-dimethylethylenediamine into this methodology.
Download or read book The Synthesis and Characterization of New Neutral Nickel Complexes Containing the Tetrathioethylene Unit written by Kimberly A. Proctor and published by . This book was released on 1995 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Biochemistry of Nickel written by Robert P. Hausinger and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this timely monograph, the author summarizes the rapidly growing body of knowledge regarding nickel by providing a balanced discussion of its harmful and beneficial effects. Coverage includes a history of nickel; the chemistry of nickel, descriptions of the four known enzymes which contain nickel; and nickel metabolism in microbes, plants, and animals. Taken as a whole, Dr. Hausinger's work will highlight key features of this important element and help define future research.
