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Full-Text Articles in Physical Sciences and Mathematics
Proton Nuclear Magnetic Resonance Investigation Of The [2fe-2s]1--Containing “Rieske-Type” Protein From Xanthobacter Strain Py2, Richard C. Holz, Frederick J. Small, Scott A. Ensign
Proton Nuclear Magnetic Resonance Investigation Of The [2fe-2s]1--Containing “Rieske-Type” Protein From Xanthobacter Strain Py2, Richard C. Holz, Frederick J. Small, Scott A. Ensign
Chemistry Faculty Research and Publications
Proton NMR spectra of the Rieske-type ferredoxin from Xanthobacter strain Py2 were recorded in both H2O and D2O buffered solutions at pH 7.2. Several well-resolved hyperfine-shifted 1H NMR signals were observed in the 90 to −20 ppm chemical shift range. Comparison of spectra recorded in H2O and D2O buffered solutions indicated that the signals at −11.4 (L) and −15.5 (M) ppm were solvent-exchangeable and thus were assigned to the two histidine Nε2H protons. The remaining observed signals were assigned based upon chemical shift, T1 values, and one-dimensional …
Spectroscopically Distinct Cobalt(Ii) Sites In Heterodimetallic Forms Of The Aminopeptidase From Aeromonas Proteolytica: Characterization Of Substrate Binding, Brian Bennett, Richard C. Holz
Spectroscopically Distinct Cobalt(Ii) Sites In Heterodimetallic Forms Of The Aminopeptidase From Aeromonas Proteolytica: Characterization Of Substrate Binding, Brian Bennett, Richard C. Holz
Physics Faculty Research and Publications
The Co(II)Zn(II)- and Zn(II)Co(II)-substituted derivatives of the aminopeptidase from Aeromonas proteolytica (AAP) were probed by EPR spectroscopy. EPR spectra of the high-spin S = 3/2 Co(II) ions in [CoZn(AAP)] and [ZnCo(AAP)] indicated that each metal binding site provides a spectroscopically distinct signature. For [CoZn(AAP)], subtraction of EPR spectra recorded at pH 7.5 and 10 revealed that two species were present and that the relative contributions to each of the experimental spectra were pH-dependent. The first EPR species, predominant at lower pH values, was simulated as a relatively featureless axial signal with geff values of 2.20, 3.92, and …
Preparation Of Organometallic Complexed Sugars: Hetero Diels−Alder Reactivity Of Tricarbonyl(Formyltrimethylenemethane)- Iron, Paul J. Kleindl, William Donaldson
Preparation Of Organometallic Complexed Sugars: Hetero Diels−Alder Reactivity Of Tricarbonyl(Formyltrimethylenemethane)- Iron, Paul J. Kleindl, William Donaldson
Chemistry Faculty Research and Publications
No abstract provided.
The Electrochemical Oxidation Of Organic Selenides And Selenoxides, Michael D. Ryan, Jiyi Yau, Michael Hack
The Electrochemical Oxidation Of Organic Selenides And Selenoxides, Michael D. Ryan, Jiyi Yau, Michael Hack
Chemistry Faculty Research and Publications
The electrochemical oxidation of alkyl and aryl selenides was investigated in acetonitrile. The oxidation of diphenyl selenide and di(4‐methylphenyl) selenide led primarily to the formation of their respective selenoxides, which were identified by exhaustive coulometric oxidation and and analysis of the products. The selenoxide itself was not observed in the cyclic voltammetry of the selenide for two reasons: first, the protonation of the selenoxide by the acid formed from the reaction of water with the cation radical and second, the formation of a selenoxide hydrate. The formation of the hydrate with diphenyl selenoxide was verified by isolation of the dimethoxy …
Mechanistic Studies On The Aminopeptidase From Aeromonas Proteolytica: A Two-Metal Ion Mechanism For Peptide Hydrolysis, Guanjing Chen, Tanya Edwards, Ventris M. D'Souza, Richard C. Holz
Mechanistic Studies On The Aminopeptidase From Aeromonas Proteolytica: A Two-Metal Ion Mechanism For Peptide Hydrolysis, Guanjing Chen, Tanya Edwards, Ventris M. D'Souza, Richard C. Holz
Chemistry Faculty Research and Publications
The aminopeptidase from Aeromonas proteolytica (AAP) is uncompetitively inhibited by fluoride ion at pH 8.0 with an inhibition constant (Ki) of 30 mM. Thus, fluoride inactivates AAP only after substrate binding, and only a single fluoride ion binds to AAP. On the other hand, chloride ion does not inhibit AAP up to concentrations of 2 M at pH 8.0. The pH dependence of fluoride inhibition of AAP was measured over the pH range 6.0−9.5. Between pH values of 6.0 and 9.0, fluoride ion acts as a pure uncompetitive inhibitor of AAP, and the Ki increases from …
Reactions Of Hydroxylamine With Metal Porphyrins, In Kyu Choi, Yanming Liu, Zhongcheng Wei, Michael D. Ryan
Reactions Of Hydroxylamine With Metal Porphyrins, In Kyu Choi, Yanming Liu, Zhongcheng Wei, Michael D. Ryan
Chemistry Faculty Research and Publications
The reaction of hydroxylamine with a series of metal porphyrins was examined in methanol/chloroform media. The reductive nitrosylation reaction was observed for the manganese and iron porphyrins, leading to a nitrosyl complex that precipitated out of the solution in good isolatable yield (80−90%). This reaction could be used synthetically for the generation of iron and manganese porphyrin nitrosyl complexes and was particularly useful for making isotopically labeled nitrosyl complexes. On the other hand, CoII(TPP) and Cr(TPP)(Cl) did not react with hydroxylamine under anaerobic conditions. With trace amounts of oxygen, the reaction of CoII(TPP) with hydroxylamine led …
Epr Studies On The Mono- And Dicobalt(Ii)-Substituted Forms Of The Aminopeptidase From Aeromonas Proteolytica. Insight Into The Catalytic Mechanism Of Dinuclear Hydrolases, Brian Bennett, Richard C. Holz
Epr Studies On The Mono- And Dicobalt(Ii)-Substituted Forms Of The Aminopeptidase From Aeromonas Proteolytica. Insight Into The Catalytic Mechanism Of Dinuclear Hydrolases, Brian Bennett, Richard C. Holz
Physics Faculty Research and Publications
The structure and function of the prototypical dinuclear hydrolase, namely, the aminopeptidase from Aeromonas proteolytica (AAP), was probed by EPR spectroscopy of the mono- and dicobalt(II)-substituted derivatives. A new systematic protocol for the interpretation of Co(II) EPR spectra is described and the S = 3/2 spin states of the Co(II)-substituted forms of the enzyme have been characterized. This protocol allows the simulation of line shape using theoretically allowed geff values corresponding to an isotropic greal value. In addition, the gross distortion of EPR spectra of high-spin S = 3/2 Co(II) ions has been investigated, …
Preparation And Reactivity Of Acyclic (Pentadienyl)Iron(1+) Cations: Applications To Organic Synthesis, William A. Donaldson
Preparation And Reactivity Of Acyclic (Pentadienyl)Iron(1+) Cations: Applications To Organic Synthesis, William A. Donaldson
Chemistry Faculty Research and Publications
No abstract provided.
N-Methylbenzothiazole-2(3H)-Selone, C8H7Nsse, Steinar Husebye, Sergey V. Lindeman, Martin D. Rudd
N-Methylbenzothiazole-2(3H)-Selone, C8H7Nsse, Steinar Husebye, Sergey V. Lindeman, Martin D. Rudd
Chemistry Faculty Research and Publications
The crystal structure of N-methyl1,3-benzothiazole-2(3H)-selone, (mbts) has been studied to estimate the changes in the molecular geometry of the mbts ligand upon coordination. Hypervalent complexes of mbts with TeII and II have been studied by us previously. A significant elongation of the Se=C bond [from 1.817 (7) in mbts to 1.85-1.88 Å in the complexes] was found, but there were no significant changes in the other geometric parameters of the ligand. The only other bond-length decrease of note was for SeC-NMe [from 1.35 (1) in mbts to 1.32-1.34 Å in the complexes]. Thus, only the …
Hexakis(Dimethylformamide)Bis(Hexaphenylcyclohexasiloxanehexaolato)Hexacopper(Ii) Dimethylformamide Solvate, Sergey V. Lindeman, Olga I. Shchegolikhina, Yulia A. Molodtsova, Alexandr A. Zhdanov
Hexakis(Dimethylformamide)Bis(Hexaphenylcyclohexasiloxanehexaolato)Hexacopper(Ii) Dimethylformamide Solvate, Sergey V. Lindeman, Olga I. Shchegolikhina, Yulia A. Molodtsova, Alexandr A. Zhdanov
Chemistry Faculty Research and Publications
The sandwich-like title complex, hexakis(dimethylformamide)-1O,2O,3O,4O,5O,6O-bis[2,4,6,8,10,12-hexaphenylsiloxane-2,4,6,8,10,12-hexaolato(6-)-1:22O1,2:32O2,3:42O3,- 4:52O4,5:62O5,1:62O6]hexacopper(II) tetrakis(dimethylformamide) solvate, [Cu6(C3H7NO)6{(C6H5)6O12Si6}2].4C3H7NO, is comprised of two regular crown-shaped macrocyclic hexadentate organosiloxanolate ligands chelating a flat Cu6 hexagon, as in the ethanol-solvated analogue investigated previously. The title complex has a more distorted shape …