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Daniel T P Stack - One of the best experts on this subject based on the ideXlab platform.

  • recent advances in phenoxyl radical complexes of salen type ligands as mixed valent galactose oxidase models
    Coordination Chemistry Reviews, 2013
    Co-Authors: Christopher T Lyons, Daniel T P Stack
    Abstract:

    The interplay between redox-active transition metal ions and redox-active ligands in metalloenzyme sites is an area of considerable research interest. Galactose oxidase (GO) is the archetypical example, catalyzing the aerobic oxidation of primary alcohols to aldehydes via two one-electron cofactors: a Copper Atom and a cysteine-modified tyrosine residue. The electronic structure of the oxidized form of the enzyme (GO(ox)) has been investigated extensively through small molecule analogues including metal-salen phenoxyl radical complexes. Similar to GO(ox), one-electron oxidized metal-salen complexes are mixed-valent species, in which molecular orbitals (MOs) with predominantly phenolate and phenoxyl π-character act as redox-active centers bridged by mixing with metal d-orbitals. A detailed evaluation of the electronic distribution in these odd electron species using a variety of spectroscopic, electrochemical, and theoretical techniques has led to keen insights into the electronic structure of GO(ox).

  • recent advances in phenoxyl radical complexes of salen type ligands as mixed valent galactose oxidase models
    Coordination Chemistry Reviews, 2013
    Co-Authors: Christopher T Lyons, Daniel T P Stack
    Abstract:

    Abstract The interplay between redox-active transition metal ions and redox-active ligands in metalloenzyme sites is an area of considerable research interest. Galactose oxidase (GO) is the archetypical example, catalyzing the aerobic oxidation of primary alcohols to aldehydes via two one-electron cofactors: a Copper Atom and a cysteine-modified tyrosine residue. The electronic structure of the oxidized form of the enzyme (GOox) has been investigated extensively through small molecule analogs including metal–salen phenoxyl radical complexes. Similar to GOox, one-electron oxidized metal–salen complexes are mixed-valent species, in which molecular orbitals (MOs) with predominantly phenolate and phenoxyl π-character act as redox-active centers bridged by mixing with metal d-orbitals. A detailed evaluation of the electronic distribution in these odd electron species using a variety of spectroscopic, electrochemical, and theoretical techniques, has led to keen insights into the electronic structure of GOox.

Christopher T Lyons - One of the best experts on this subject based on the ideXlab platform.

  • recent advances in phenoxyl radical complexes of salen type ligands as mixed valent galactose oxidase models
    Coordination Chemistry Reviews, 2013
    Co-Authors: Christopher T Lyons, Daniel T P Stack
    Abstract:

    The interplay between redox-active transition metal ions and redox-active ligands in metalloenzyme sites is an area of considerable research interest. Galactose oxidase (GO) is the archetypical example, catalyzing the aerobic oxidation of primary alcohols to aldehydes via two one-electron cofactors: a Copper Atom and a cysteine-modified tyrosine residue. The electronic structure of the oxidized form of the enzyme (GO(ox)) has been investigated extensively through small molecule analogues including metal-salen phenoxyl radical complexes. Similar to GO(ox), one-electron oxidized metal-salen complexes are mixed-valent species, in which molecular orbitals (MOs) with predominantly phenolate and phenoxyl π-character act as redox-active centers bridged by mixing with metal d-orbitals. A detailed evaluation of the electronic distribution in these odd electron species using a variety of spectroscopic, electrochemical, and theoretical techniques has led to keen insights into the electronic structure of GO(ox).

  • recent advances in phenoxyl radical complexes of salen type ligands as mixed valent galactose oxidase models
    Coordination Chemistry Reviews, 2013
    Co-Authors: Christopher T Lyons, Daniel T P Stack
    Abstract:

    Abstract The interplay between redox-active transition metal ions and redox-active ligands in metalloenzyme sites is an area of considerable research interest. Galactose oxidase (GO) is the archetypical example, catalyzing the aerobic oxidation of primary alcohols to aldehydes via two one-electron cofactors: a Copper Atom and a cysteine-modified tyrosine residue. The electronic structure of the oxidized form of the enzyme (GOox) has been investigated extensively through small molecule analogs including metal–salen phenoxyl radical complexes. Similar to GOox, one-electron oxidized metal–salen complexes are mixed-valent species, in which molecular orbitals (MOs) with predominantly phenolate and phenoxyl π-character act as redox-active centers bridged by mixing with metal d-orbitals. A detailed evaluation of the electronic distribution in these odd electron species using a variety of spectroscopic, electrochemical, and theoretical techniques, has led to keen insights into the electronic structure of GOox.

David S Sholl - One of the best experts on this subject based on the ideXlab platform.

  • prediction of water adsorption in Copper based metal organic frameworks using force fields derived from dispersion corrected dft calculations
    Journal of Physical Chemistry C, 2013
    Co-Authors: Ji Zang, Sankar Nair, David S Sholl
    Abstract:

    We develop transferable force fields describing water adsorption in Copper-based metal–organic frameworks (MOFs) by combining dispersion-corrected density functional theory (DFT) calculations and classical Atomistic simulations. The DFT-D2 approach was found to give reasonable agreement with high level quantum chemistry results for the interaction between water and CuBTC. A classical force field for water adsorption in CuBTC including Lennard-Jones (LJ), Coulombic interactions, and a water–Copper distance-dependent correction term was then developed on the basis of 1200 DFT-D2 calculations that probed the full range of accessible volume in CuBTC via random sampling. Good agreement was obtained between adsorption isotherms predicted with our first-principles-derived force field and experiments. Other commonly used models such as simple combinations of LJ and Coulomb potentials cannot adequately describe the interaction between water and CuBTC due to the chemical bonding between water oxygen and Copper Atom...

Christian Leitner - One of the best experts on this subject based on the ideXlab platform.

  • galactose oxidase from fusarium oxysporum expression in e coli and p pastoris and biochemical characterization
    PLOS ONE, 2014
    Co-Authors: Regina Paukner, Petra Staudigl, Withu Choosri, Christoph Sygmund, Petr Halada, Dietmar Haltrich, Christian Leitner
    Abstract:

    A gene coding for galactose 6-oxidase from Fusarium oxysporum G12 was cloned together with its native preprosequence and a C-terminal His-tag, and successfully expressed both in Escherichia coli and Pichia pastoris. The enzyme was subsequently purified and characterized. Among all tested substrates, the highest catalytic efficiency (kcat/Km) was found with 1-methyl-β-D-galactopyranoside (2.2 mM−1 s−1). The Michaelis constant (Km) for D-galactose was determined to be 47 mM. Optimal pH and temperature for the enzyme activity were 7.0 and 40°C, respectively, and the enzyme was thermoinactivated at temperatures above 50°C. GalOx contains a unique metalloradical complex consisting of a Copper Atom and a tyrosine residue covalently attached to the sulphur of a cysteine. The correct formation of this thioether bond during the heterologous expression in E. coli and P. pastoris could be unequivocally confirmed by MALDI mass spectrometry, which offers a convenient alternative to prove this Tyr-Cys crosslink, which is essential for the catalytic activity of GalOx.

J W Whittaker - One of the best experts on this subject based on the ideXlab platform.