Journal ArticleDOI
X-ray absorption edge determination of the oxidation state and coordination number of copper: application to the type 3 site in Rhus vernicifera laccase and its reaction with oxygen
Lung Shan Kau,Darlene J. Spira-Solomon,James E. Penner-Hahn,Keith O. Hodgson,Edward I. Solomon +4 more
Reads0
Chats0
TLDR
In this paper, a normalized difference edge analysis is used to quantitatively determine the oxidation states of the copper sites in type 2 copper-depleted (T2D) and native forms of the multicopper oxidase, Rhus vernicifera laccase.Abstract:
Cu X-ray absorption edge features of 19 Cu(I) and 40 Cu(II) model complexes have been systematically studied and correlated with oxidation state and geometry. Studies of Cu(I) model complexes with different coordination number reveal that an 8983-8984-eV peak (assigned as the Cu 1s ..-->.. 4p transition) can be correlated in energy, shape, and intensity with ligation and site geometry of the cuprous ion. These Cu(I) edge features have been qualitatively interpreted with ligand field concepts. Alternatively, no Cu(II) complex exhibits a peak below 8985.0 eV. The limited intensity observed in the 8983-8985-eV region for some Cu(II) complexes is associated with the tail of an absorption peak at approx. 8986 eV which is affected by the covalency of the equatorial ligands. These models studies allow accurate calibration of a normalized difference edge procedure which is used for the quantitative determination of Cu(I) content in copper complexes of mixed oxidation state composition. This normalized difference edge analysis is then used to quantitatively determine the oxidation states of the copper sites in type 2 copper-depleted (T2D) and native forms of the multicopper oxidase, Rhus vernicifera laccase. The type 3 site of the T2D laccase is found to be fully reduced and stable tomore » oxidation by O/sub 2/ or by 25-fold protein equivalents of ferricyanide, but it can be oxidized by reaction with peroxide. The increase in intensity of the 330-nm absorption feature which results from peroxide titration of T2D laccase is found to correlate linearly with the percent of oxidation of the binuclear copper site.« lessread more
Citations
More filters
Journal ArticleDOI
Oxidized Derivatives of Octopus vulgaris and Carcinus aestuarii Hemocyanins at pH 7.5 and Related Models by X-ray Absorption Spectroscopy
Elena Borghi,Pier Lorenzo Solari,Pier Lorenzo Solari,Mariano Beltramini,Luigi Bubacco,Paolo Di Muro,Benedetto Salvato +6 more
TL;DR: Comparison between the protein's and the complexes' data, support a description of the met-derivatives as a five-coordinated O-bridged binuclear copper(II) center and favors, for both species, a bis(hydroxo) structure with a 3-A Cu-Cu distance.
Journal ArticleDOI
Nature and role of active states of Pd and Cu in the oxidative carbonylation of phenols with Pd/C and cuprous oxide
TL;DR: In this paper, the active states of palladium and copper for the oxidative carbonylation of phenol and bisphenol-A were investigated using X-ray absorption near-edge structure (XANES) and extended Xray absorption fine structure (EXAFS) for Pd and Cu K -edges.
Journal ArticleDOI
Structures and Catalytic Properties of Cr–Cu Embedded CeO2 Surfaces with Different Cr/Cu Ratios
Hiroshi Yoshida,Hiroshi Yoshida,Yuri Okabe,Satoshi Misumi,Haruka Oyama,Kaori Tokusada,Satoshi Hinokuma,Satoshi Hinokuma,Masato Machida,Masato Machida +9 more
TL;DR: In this article, the effects of the Cr/Cu ratios of Cr-Cu-embedded CeO2 surfaces (0.065 wt % Cu loading) on their local structures and catalytic activities were studied using experimental and theoretical approaches.
Journal ArticleDOI
Probing Physical Oxidation State by Resonant X-ray Emission Spectroscopy: Applications to Iron Model Complexes and Nitrogenase
Rebeca G. Castillo,Anselm W. Hahn,Benjamin E. Van Kuiken,Justin T. Henthorn,Jeremy McGale,Serena DeBeer +5 more
TL;DR: In this article, the ability of resonant X-ray emission spectroscopy (XES) to recover physical oxidation state information, which may often be ambiguous in conventional XAS, is demonstrated by combining Kβ XES with resonant excitation in the XAS pre-edge region.
Journal ArticleDOI
Prominent redox feature of copper ion exchanged in ZSM-5-type zeolite
TL;DR: In this article, the redox features of copper ion exchanged in ZSM-5 were investigated in both evacuation-oxidation-re-evacuation and evacuation-hydration-revacuation processes.
Related Papers (5)
ATHENA, ARTEMIS, HEPHAESTUS: data analysis for X-ray absorption spectroscopy using IFEFFIT.
Bruce Ravel,Matthew Newville +1 more