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Full-Text Articles in Physical Sciences and Mathematics
Altering The Coordination Of Iron Porphyrins By Ionic Liquid Nanodomains In Mixed Solvent Systems, Abderrahman Atifi, Michael D. Ryan
Altering The Coordination Of Iron Porphyrins By Ionic Liquid Nanodomains In Mixed Solvent Systems, Abderrahman Atifi, Michael D. Ryan
Chemistry Faculty Research and Publications
The solvent environment around iron porphyrin complexes was examined using mixed molecular/RTIL (room temperature ionic liquid) solutions. The formation of nanodomains in these solutions provides different solvation environments for substrates that could have significant impact on their chemical reactivity. Iron porphyrins (Fe(P)), whose properties are sensitive to solvent and ligation changes, were used to probe the molecular/RTIL environment. The addition of RTILs to molecular solvents shifted the redox potentials to more positive values. When there was no ligation change upon reduction, the shift in the E° values were correlated to the Gutmann acceptor number, as was observed for other …
Synthetic, Spectroscopic And Dft Studies Of Iron Complexes With Iminobenzo(Semi)Quinone Ligands: Implications For O-Aminophenol Dioxygenases, Michael M. Bittner, David S. Krause, Sergey V. Lindeman, Cordina V. Popescu, Adam T. Fiedler
Synthetic, Spectroscopic And Dft Studies Of Iron Complexes With Iminobenzo(Semi)Quinone Ligands: Implications For O-Aminophenol Dioxygenases, Michael M. Bittner, David S. Krause, Sergey V. Lindeman, Cordina V. Popescu, Adam T. Fiedler
Chemistry Faculty Research and Publications
The oxidative CC bond cleavage of o-aminophenols by nonheme Fe dioxygenases is a critical step in both human metabolism (the kynurenine pathway) and the microbial degradation of nitroaromatic pollutants. The catalytic cycle of o-aminophenol dioxygenases (APDOs) has been proposed to involve formation of an FeII/O2/iminobenzosemiquinone complex, although the presence of a substrate radical has been called into question by studies of related ring-cleaving dioxygenases. Recently, we reported the first synthesis of an iron(II) complex coordinated to an iminobenzosemiquinone (ISQ) ligand, namely, [Fe(Tp)(tBuISQ)] (2 a; where Tp=hydrotris(3,5-diphenylpyrazol-1-yl)borate and tBu …
Identification Of An Active Site-Bound Nitrile Hydratase Intermediate Through Single Turnover Stopped-Flow Spectroscopy, Natalie Gumataotao, Misty L. Kuhn, Natalia Hajnas, Richard C. Holz
Identification Of An Active Site-Bound Nitrile Hydratase Intermediate Through Single Turnover Stopped-Flow Spectroscopy, Natalie Gumataotao, Misty L. Kuhn, Natalia Hajnas, Richard C. Holz
Chemistry Faculty Research and Publications
Stopped-flow kinetic data were obtained for the iron-type nitrile hydratase from Rhodococcus equi TG328-2 (ReNHase) using methacrylonitrile as the substrate. Multiple turnover experiments suggest a three-step kinetic model that allows for the reversible binding of substrate, the presence of an intermediate, and the formation of product. Microscopic rate constants determined from these data are in good agreement with steady state data confirming that the stopped-flow method used was appropriate for the reaction. Single turnover stopped-flow experiments were used to identify catalytic intermediates. These data were globally fit confirming a three-step kinetic model. Independent absorption spectra acquired between 0.005 …
The Fe-Type Nitrile Hydratase From Comamonas Testosteroni Ni1 Does Not Require An Activator Accessory Protein For Expression In Escherichia Coli, Misty L. Kuhn, Salette Martinez, Natalie Gumataotao, Uwe Bornscheuer, Dali Liu, Richard C. Holz
The Fe-Type Nitrile Hydratase From Comamonas Testosteroni Ni1 Does Not Require An Activator Accessory Protein For Expression In Escherichia Coli, Misty L. Kuhn, Salette Martinez, Natalie Gumataotao, Uwe Bornscheuer, Dali Liu, Richard C. Holz
Chemistry Faculty Research and Publications
We report herein the functional expression of an Fe-type nitrile hydratase (NHase) without the co-expression of an activator protein or the Escherichia coli chaperone proteins GroES/EL. Soluble protein was obtained when the α- and β-subunit genes of the Fe-type NHase Comamonas testosteroni Ni1 (CtNHase) were synthesized with optimized E. coli codon usage and co-expressed. As a control, the Fe-type NHase from Rhodococcus equi TG328–2 (ReNHase) was expressed with (ReNHase+Act) and without (ReNHase−Act) its activator protein, establishing that expression of a fully functional, metallated ReNHase enzyme requires the …
Synthesis And Structural Characterization Of Iron(Ii) Complexes With Tris(Imidazolyl)Phosphane Ligands: A Platform For Modeling The 3-Histidine Facial Triad Of Nonheme Iron Dioxygenases, Michael M. Bittner, Jacob Baus, Sergey V. Lindeman, Adam T. Fiedler
Synthesis And Structural Characterization Of Iron(Ii) Complexes With Tris(Imidazolyl)Phosphane Ligands: A Platform For Modeling The 3-Histidine Facial Triad Of Nonheme Iron Dioxygenases, Michael M. Bittner, Jacob Baus, Sergey V. Lindeman, Adam T. Fiedler
Chemistry Faculty Research and Publications
Several monoiron(II) complexes containing tris(imidazolyl)phosphane (TIP) ligands have been prepared and structurally characterized by using X-ray crystallography and NMR spectroscopy. Two TIP ligands were employed: tris(2-phenylimidazol-4-yl)phosphane (4-TIPPh) and tris(4,5-diphenyl-1-methylimidazol-2-yl)phosphane (2-TIPPh2). These tridentate ligands resemble the 3-histidine (3His) facial triad found recently in the active sites of certain nonheme iron dioxygenases. Three of the reported complexes are designed to serve as convenient precursors to species that model the enzyme–substrate intermediates of 3His dioxygenases; thus, each contains an [Fe(κ3-TIP)]2+ unit in which the remaining coordination sites are occupied by easily displaced ligands, such as solvent …
Recent Applications Of Acyclic (Diene)Iron Complexes And (Dienyl)Iron Cations In Organic Synthesis, William Donaldson, Subhabrata Chaudhury
Recent Applications Of Acyclic (Diene)Iron Complexes And (Dienyl)Iron Cations In Organic Synthesis, William Donaldson, Subhabrata Chaudhury
Chemistry Faculty Research and Publications
Complexation of (tricarbonyl)iron to an acyclic diene serves to protect the ligand against oxidation, reduction, and cycloaddition reactions, whereas the steric bulk of this adjunct serves to direct the approaches of reagents to unsaturated groups attached to the diene onto the face opposite to iron. Furthermore, the Fe(CO)3 moiety can serve to stabilize carbocation centers adjacent to the diene (i.e. pentadienyl-iron cations). Recent applications of these reactivities to the synthesis of polyene-, cyclopropane-, cycloheptadiene-, and cyclohexenone-containing natural products or analogues are presented.