Active Sites In Copper Proteins Research Articles

Preparation and Characterization of Nicotinium Tetrahalocuprate(II) and Tetrahalocobaltate(II) Complexes : Structure of Nicotinium Tetrachlorocobaltate(II)

Nicotine (C10H14N2, nic) is one of the alkaloids well recognized for it's toxin activity, and it's chemistry is an important topic because of its health implications. Nicotine possesses the methylated pyrrolidine nitrogen (pKb1 = 6.16) and the less basic pyridine nitrogen (pKb2 = 10.96), thus it forms a chelate complex resulting in a CuN2X2 chromophore when it reacts with the copper(II) halides. The complex shows a distorted tetrahedral geometry around the copper(II) site (C2v) due to the steric hindrance of the nicotine ligand in the resulting chelate complex. Double protonation of nicotine gives a nicotinium cation, nicH2, which is expected to form easily into crystalline salts with tetrahalometallate(II) anions of the general formula [C10H16N2][MX4]. Recently we reported on the single crystal structure of (nicH2)CuCl4. The crystal exhibited two crystallographically non-equivalent pseudotetrahedral [CuCl4] anions, each of which was linked to two doubly protonated nicotinium cations via hydrogen bonds. The pseudotetrahedral (D2d) geometry around the Cu(II) site in (nicH2)CuCl4 arose from the packing effect caused from the large nicH cation size as well as the strong hydrogen bonding networks between the protonated nicotinium cation and the chloride atoms in [CuCl4]. The pseudotetrahedral copper(II) complexes were interesting in that they were proposed as a mimic compound of active sites in copper proteins. Herein, we investigate the optical and magnetic properties of (nicH2)CuX4 (X=Cl, Br) complexes, and elucidate the observed properties in accordance with the corresponding pseudotetrahedral geometry of the Cu(II) site in the prepared complexes. Furthermore, we synthesize a nicotinium tetrahalocobaltate(II), (nicH2)CoX4 complex. We report on the single crystal structure of the nicotinium tetrachlorocobaltate(II) complex and compare it to that of (nicH2)CuCl4 complex. The optical and magnetic properties of (nicH2)CoCl4 were examined and explained as a symmetric [CoCl4] unit.

Bio-mimicking galactose oxidase and hemocyanin, two dioxygen-processing copper proteins

The modelling of the active sites of metalloproteins is one of the most challenging tasks in bio-inorganic chemistry. Copper proteins form part of this stimulating field of research as copper enzymes are mainly involved in oxidation bio-reactions. Thus, the understanding of the structure-function relationship of their active sites will allow the design of effective and environmental friendly oxidation catalysts. This perspective illustrates some outstanding structural and functional synthetic models of the active site of copper proteins, with special attention given to models of galactose oxidase and hemocyanin.

Investigation of the active site of copper proteins: the structure of some model complexes determined by x-ray diffraction and absorption spectroscopy

Resume Les structures tridimensionnelles de complexes de cuivre (I) et (II), determinees par diffraction X et par spectroscopie d'absorption X (EXAFS), sont decrites.

Electronic structures of active sites in copper proteins: Contributions to reactivity

Electronic structures of active sites in copper proteins: Contributions to reactivity

Coordination compounds of tripeptides and pentapeptides containing L‐histidyl residues. Studies towards structural models for the active site of copper proteins

AbstractFive small, completely protected, L‐histidyl(NτBzl)‐containing peptides, were synthesized and characterized by NMR spectroscopy, i.e., R‐Ala‐His(Nτ‐Bzl)‐Ala‐R′ (1), R‐His(Nτ‐Bzl)‐Ala‐Ala‐Ala‐Met‐R′ (2), R‐His(Nτ‐Bzl)‐Ala‐Ala‐Ala‐His(Nτ‐Bzl)‐R′ (3), R‐His(Nτ‐Bzl)‐Ala‐His(Nτ‐Bzl)‐Ala‐His(Nτ‐Bzl)‐R′ (4), R‐His(Nτ‐Bzl)‐Ala‐His(Nτ‐Bzl)‐R′ (5), in which: R is phenylacetyl (PhCH2CO‐), R′ is phenylamino (‐NHPh); Bzl is benzyl (PhCH2‐).It has been shown that benzylation of histidine residues takes place at the Nτ atom of the imidazole. The resulting peptide derivatives appear to be good ligands for CoII, ZnII and CuI. Titrations of zinc chloride solutions towards peptide solutions (in dmso‐d6, dimethyl sulfoxide followed by NMR spectroscopy show the formation of the two species [Zn(NπHis)2Cl2] and [Zn(NπHis)(dmso)Cl2]. Copper(I)‐chloride titrations result in formation of trigonal planar and tetrahedral complexes (in dmso‐d6). Zinc, copper and cobalt trifluoromethanesulfonates were also investigated, and corresponding tetrahedral species with additional dmso ligands replacing chloride were obtained. In addition, octahedral complexes have been found, as shown for cobalt(II) using ligand‐field spectroscopy.Conductivity experiments of zinc chloride complexes in dmso and chloroform indicate non‐electrolytes. Their very low conductivity in methanol indicates only slight dissociation of chloride, in agreement with a tetrahedral geometry for zinc(II). For [Co(NπHis)2Cl2], the UV‐VIS adsorption spectra in dmso and in the solid state (diffuse reflection) are comparable, indicating tetrahedral geometry, with a CoN2Cl2 chromophore.

Electronic structures of active sites in copper proteins: Contributions to reactivity

Electronic structures of active sites in copper proteins: Contributions to reactivity

Characterization of mononuclear copper-nitrogen oxide complexes: Models of NO x binding to isolated active sites in copper proteins

Detailed examination of the interactions of simple nitrogen oxides, NxOy n-, with metal ions has become increasingly important for understanding the role of NxOy n-species in numerous biochemically and environmentally significant processes. Metal-mediated reactions of nitrogen oxides are ubiquitous within the global nitrogen cycle, in which the various forms of nitrogen are interconverted and distributed throughout the world.1 For example, metalloenzymes containing molybdenum, iron, or copper are involved in every stage of denitrification, the dissimilatory process by which some bacteria use NO3 - and NO2 - as terminal electron acceptors to release gaseous NO, N2O, and N2 (Figure 1).2 Environmental consequences of denitrification include the depletion of sources of nitrogen necessary for plant growth and the production of the greenhouse gas and ozone destroyer N2O. Moreover, excess NO3 -, a pollutant that contributes to eutrophication of lakes and rivers, can be removed from waste water by denitrification in a useful bioremedial application.3

Electronic structures of active sites in copper proteins: contributions to reactivity

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectronic structures of active sites in copper proteins: contributions to reactivityEdward I. Solomon, Michael J. Baldwin, and Michael D. LoweryCite this: Chem. Rev. 1992, 92, 4, 521–542Publication Date (Print):June 1, 1992Publication History Published online1 May 2002Published inissue 1 June 1992https://doi.org/10.1021/cr00012a003RIGHTS & PERMISSIONSArticle Views3265Altmetric-Citations750LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (6 MB) Get e-Alerts Get e-Alerts

Synthetic approach to the type 1 active site of copper proteins. Copper(I), copper(II), and zinc(II) complexes with N2SS* ligand donor sets

Preparation des complexes de Cu(I et II) et Zn(II) du coordinat forme par condensation en phenyl-1 formyl-3 pyridine-2 (1H) thione et {[(amino-2 ethyl) thio] methyl}-4 methyl-5 imidazole. Il semble que Zn(II) prefere se fixer au N de l'imine et Cu (I) au S du thioether. Spectres UV-visible et RPE

Temperature dependence of the ligand field strength in systems with modulated potential-energy surfaces. A suggestion for interpreting spectroscopic properties of metalloproteins

Abstract The structural and spectroscopic properties of physical systems having different potential-energy wells are strongly affected by temperature where energy barriers are comparable to the thermal energy. A theoretical analysis has been performed using an asymmetric double-well potential and, on the basis of the results obtained, an interpretation of the temperature-dependent properties of some real systems, such as the active sites in copper proteins, is proposed.