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Harry B. Gray - One of the best experts on this subject based on the ideXlab platform.

  • inner and outer sphere metal coordination in blue Copper Proteins
    Journal of Inorganic Biochemistry, 2012
    Co-Authors: Jeffrey J Warren, Kyle M Lancaster, John H Richards, Harry B. Gray
    Abstract:

    Blue Copper Proteins (BCPs) comprise classic cases of Nature's profound control over the electronic structures and chemical reactivity of transition metal ions. Early studies of BCPs focused on their inner coordination spheres, that is, residues that directly coordinate Cu. Equally important are the electronic and geometric perturbations to these ligands provided by the outer coordination sphere. In this tribute to Hans Freeman, we review investigations that have advanced the understanding of how inner-sphere and outer-sphere coordination affects biological Cu properties.

  • outer sphere contributions to the electronic structure of type zero Copper Proteins
    Journal of the American Chemical Society, 2012
    Co-Authors: Kyle M Lancaster, Alejandro J. Vila, John H Richards, Mariaeugenia Zaballa, Stephen Sproules, Mahesh Sundararajan, Serena Debeer, Frank Neese, Harry B. Gray
    Abstract:

    Bioinorganic canon states that active-site thiolate coordination promotes rapid electron transfer (ET) to and from type 1 Copper Proteins. In recent work, we have found that Copper ET sites in Proteins also can be constructed without thiolate ligation (called “type zero” sites). Here we report multifrequency electron paramagnetic resonance (EPR), magnetic circular dichroism (MCD), and nuclear magnetic resonance (NMR) spectroscopic data together with density functional theory (DFT) and spectroscopy-oriented configuration interaction (SORCI) calculations for type zero Pseudomonas aeruginosa azurin variants. Wild-type (type 1) and type zero Copper centers experience virtually identical ligand fields. Moreover, O-donor covalency is enhanced in type zero centers relative that in the C112D (type 2) protein. At the same time, N-donor covalency is reduced in a similar fashion to type 1 centers. QM/MM and SORCI calculations show that the electronic structures of type zero and type 2 are intimately linked to the orientation and coordination mode of the carboxylate ligand, which in turn is influenced by outer-sphere hydrogen bonding.

  • Electron Flow through Iron and Copper Proteins
    Bulletin of Japan Society of Coordination Chemistry, 2011
    Co-Authors: Andrew K. Udit, Michael G. Hill, Jay R. Winkler, Harry B. Gray
    Abstract:

    Employing laser flash-quench triggering methods, we have shown that 20-angstrom, coupling-limited Cu(I) to Ru(III) electron tunneling in Ru-modified blue Copper Proteins can occur on the microsecond timescale both in solutions and crystals. Redox equivalents can be transferred even longer distances by multistep tunneling, often called hopping, through intervening amino acid side chains. The lessons we have learned about the control of electron tunneling and hopping through biological molecules are now guiding the construction of wired and sensitizer-modified P450s for investigations of electrocatalysis and photocatalysis of oxygenation reactions.

  • type zero Copper Proteins
    Nature Chemistry, 2009
    Co-Authors: Kyle M Lancaster, Serena Debeer George, John H Richards, Keiko Yokoyama, Harry B. Gray
    Abstract:

    Many Proteins contain Copper in a range of coordination environments, where it has various biological roles, such as transferring electrons or activating dioxygen. These Copper sites can be classified by their function or spectroscopic properties. Those with a single Copper atom are either type 1, with an intense absorption band near 600 nm, or type 2, with weak absorption in the visible region. We have built a novel Copper(ii) binding site within structurally modified Pseudomonas aeruginosa azurins that does not resemble either existing type, which we therefore call 'type zero'. X-ray crystallographic analysis shows that these sites adopt distorted tetrahedral geometries, with an unusually short Cu–O (G45 carbonyl) bond. Relatively weak absorption near 800 nm and narrow parallel hyperfine splittings in electron paramagnetic resonance spectra are the spectroscopic signatures of type zero Copper. Cyclic voltammetric experiments demonstrate that the electron transfer reactivities of type-zero azurins are enhanced relative to that of the corresponding type 2 (C112D) protein.

Kyle M Lancaster - One of the best experts on this subject based on the ideXlab platform.

  • inner and outer sphere metal coordination in blue Copper Proteins
    Journal of Inorganic Biochemistry, 2012
    Co-Authors: Jeffrey J Warren, Kyle M Lancaster, John H Richards, Harry B. Gray
    Abstract:

    Blue Copper Proteins (BCPs) comprise classic cases of Nature's profound control over the electronic structures and chemical reactivity of transition metal ions. Early studies of BCPs focused on their inner coordination spheres, that is, residues that directly coordinate Cu. Equally important are the electronic and geometric perturbations to these ligands provided by the outer coordination sphere. In this tribute to Hans Freeman, we review investigations that have advanced the understanding of how inner-sphere and outer-sphere coordination affects biological Cu properties.

  • outer sphere contributions to the electronic structure of type zero Copper Proteins
    Journal of the American Chemical Society, 2012
    Co-Authors: Kyle M Lancaster, Alejandro J. Vila, John H Richards, Mariaeugenia Zaballa, Stephen Sproules, Mahesh Sundararajan, Serena Debeer, Frank Neese, Harry B. Gray
    Abstract:

    Bioinorganic canon states that active-site thiolate coordination promotes rapid electron transfer (ET) to and from type 1 Copper Proteins. In recent work, we have found that Copper ET sites in Proteins also can be constructed without thiolate ligation (called “type zero” sites). Here we report multifrequency electron paramagnetic resonance (EPR), magnetic circular dichroism (MCD), and nuclear magnetic resonance (NMR) spectroscopic data together with density functional theory (DFT) and spectroscopy-oriented configuration interaction (SORCI) calculations for type zero Pseudomonas aeruginosa azurin variants. Wild-type (type 1) and type zero Copper centers experience virtually identical ligand fields. Moreover, O-donor covalency is enhanced in type zero centers relative that in the C112D (type 2) protein. At the same time, N-donor covalency is reduced in a similar fashion to type 1 centers. QM/MM and SORCI calculations show that the electronic structures of type zero and type 2 are intimately linked to the orientation and coordination mode of the carboxylate ligand, which in turn is influenced by outer-sphere hydrogen bonding.

  • type zero Copper Proteins
    Nature Chemistry, 2009
    Co-Authors: Kyle M Lancaster, Serena Debeer George, John H Richards, Keiko Yokoyama, Harry B. Gray
    Abstract:

    Many Proteins contain Copper in a range of coordination environments, where it has various biological roles, such as transferring electrons or activating dioxygen. These Copper sites can be classified by their function or spectroscopic properties. Those with a single Copper atom are either type 1, with an intense absorption band near 600 nm, or type 2, with weak absorption in the visible region. We have built a novel Copper(ii) binding site within structurally modified Pseudomonas aeruginosa azurins that does not resemble either existing type, which we therefore call 'type zero'. X-ray crystallographic analysis shows that these sites adopt distorted tetrahedral geometries, with an unusually short Cu–O (G45 carbonyl) bond. Relatively weak absorption near 800 nm and narrow parallel hyperfine splittings in electron paramagnetic resonance spectra are the spectroscopic signatures of type zero Copper. Cyclic voltammetric experiments demonstrate that the electron transfer reactivities of type-zero azurins are enhanced relative to that of the corresponding type 2 (C112D) protein.

John H Richards - One of the best experts on this subject based on the ideXlab platform.

  • inner and outer sphere metal coordination in blue Copper Proteins
    Journal of Inorganic Biochemistry, 2012
    Co-Authors: Jeffrey J Warren, Kyle M Lancaster, John H Richards, Harry B. Gray
    Abstract:

    Blue Copper Proteins (BCPs) comprise classic cases of Nature's profound control over the electronic structures and chemical reactivity of transition metal ions. Early studies of BCPs focused on their inner coordination spheres, that is, residues that directly coordinate Cu. Equally important are the electronic and geometric perturbations to these ligands provided by the outer coordination sphere. In this tribute to Hans Freeman, we review investigations that have advanced the understanding of how inner-sphere and outer-sphere coordination affects biological Cu properties.

  • outer sphere contributions to the electronic structure of type zero Copper Proteins
    Journal of the American Chemical Society, 2012
    Co-Authors: Kyle M Lancaster, Alejandro J. Vila, John H Richards, Mariaeugenia Zaballa, Stephen Sproules, Mahesh Sundararajan, Serena Debeer, Frank Neese, Harry B. Gray
    Abstract:

    Bioinorganic canon states that active-site thiolate coordination promotes rapid electron transfer (ET) to and from type 1 Copper Proteins. In recent work, we have found that Copper ET sites in Proteins also can be constructed without thiolate ligation (called “type zero” sites). Here we report multifrequency electron paramagnetic resonance (EPR), magnetic circular dichroism (MCD), and nuclear magnetic resonance (NMR) spectroscopic data together with density functional theory (DFT) and spectroscopy-oriented configuration interaction (SORCI) calculations for type zero Pseudomonas aeruginosa azurin variants. Wild-type (type 1) and type zero Copper centers experience virtually identical ligand fields. Moreover, O-donor covalency is enhanced in type zero centers relative that in the C112D (type 2) protein. At the same time, N-donor covalency is reduced in a similar fashion to type 1 centers. QM/MM and SORCI calculations show that the electronic structures of type zero and type 2 are intimately linked to the orientation and coordination mode of the carboxylate ligand, which in turn is influenced by outer-sphere hydrogen bonding.

  • type zero Copper Proteins
    Nature Chemistry, 2009
    Co-Authors: Kyle M Lancaster, Serena Debeer George, John H Richards, Keiko Yokoyama, Harry B. Gray
    Abstract:

    Many Proteins contain Copper in a range of coordination environments, where it has various biological roles, such as transferring electrons or activating dioxygen. These Copper sites can be classified by their function or spectroscopic properties. Those with a single Copper atom are either type 1, with an intense absorption band near 600 nm, or type 2, with weak absorption in the visible region. We have built a novel Copper(ii) binding site within structurally modified Pseudomonas aeruginosa azurins that does not resemble either existing type, which we therefore call 'type zero'. X-ray crystallographic analysis shows that these sites adopt distorted tetrahedral geometries, with an unusually short Cu–O (G45 carbonyl) bond. Relatively weak absorption near 800 nm and narrow parallel hyperfine splittings in electron paramagnetic resonance spectra are the spectroscopic signatures of type zero Copper. Cyclic voltammetric experiments demonstrate that the electron transfer reactivities of type-zero azurins are enhanced relative to that of the corresponding type 2 (C112D) protein.

Katherine J. Franz - One of the best experts on this subject based on the ideXlab platform.

  • coordination chemistry of Copper Proteins how nature handles a toxic cargo for essential function
    Journal of Inorganic Biochemistry, 2012
    Co-Authors: Jeffrey T. Rubino, Katherine J. Franz
    Abstract:

    Abstract Biological Copper is coordinated predominantly by just three ligand types: the side chains of histidine, cysteine, and methionine, with of course some exceptions. The arrangement of these components, however, is fascinating. The diversity provided by just these three ligands provides choices of nitrogen vs. sulfur, neutral vs. charged, hydrophilic vs. hydrophobic, susceptibility to oxidation, and degree of pH-sensitivity. In this review we examine how the total number of ligands, their spatial arrangement and solvent accessibility, the various combinations of imidazole, thiolate, and thioether donors, all work together to provide binding sites that either enable Copper to carry out a function, or safely transport it in a way that prevents toxic reactivity. We separate Copper Proteins into two broad classes, those that utilize the metal as a cofactor, or those that traffic the metal. Enzymes and Proteins that utilize Copper as a cofactor use high affinity sites of high coordination numbers of 4–5 that prevent loss of the metal during redox cycling. Copper trafficking Proteins, on the other hand, promote metal transfer either by having low affinity binding sites with moderate coordination number ~ 4, or by having lower coordinate binding sites of 2–3 ligands that bind with high affinity. Both strategies retain the metal but allow transfer under appropriate conditions. Analysis of studies from our own lab on model peptides, combined with those from other labs, raises an interesting hypothesis that various methionine/histidine/cysteine combinations provide organisms with dynamic, multifunctional domains on Copper trafficking Proteins that facilitate Copper transfer under different extracellular, subcellular, and tissue-specific scenarios of pH, redox environment, and presence of other Copper carriers or target Proteins.

  • Coordination chemistry of Copper Proteins: How nature handles a toxic cargo for essential function
    Journal of Inorganic Biochemistry, 2012
    Co-Authors: Jeffrey T. Rubino, Katherine J. Franz
    Abstract:

    Biological Copper is coordinated predominantly by just three ligand types: the side chains of histidine, cysteine, and methionine, with of course some exceptions. The arrangement of these components, however, is fascinating. The diversity provided by just these three ligands provides choices of nitrogen vs. sulfur, neutral vs. charged, hydrophilic vs. hydrophobic, susceptibility to oxidation, and degree of pH-sensitivity. In this review we examine how the total number of ligands, their spatial arrangement and solvent accessibility, the various combinations of imidazole, thiolate, and thioether donors, all work together to provide binding sites that either enable Copper to carry out a function, or safely transport it in a way that prevents toxic reactivity. We separate Copper Proteins into two broad classes, those that utilize the metal as a cofactor, or those that traffic the metal. Enzymes and Proteins that utilize Copper as a cofactor use high affinity sites of high coordination numbers of 4-5 that prevent loss of the metal during redox cycling. Copper trafficking Proteins, on the other hand, promote metal transfer either by having low affinity binding sites with moderate coordination number ~ 4, or by having lower coordinate binding sites of 2-3 ligands that bind with high affinity. Both strategies retain the metal but allow transfer under appropriate conditions. Analysis of studies from our own lab on model peptides, combined with those from other labs, raises an interesting hypothesis that various methionine/histidine/ cysteine combinations provide organisms with dynamic, multifunctional domains on Copper trafficking Proteins that facilitate Copper transfer under different extracellular, subcellular, and tissue-specific scenarios of pH, redox environment, and presence of other Copper carriers or target Proteins. © 2011 Elsevier Inc. All rights reserved.

Serena Debeer George - One of the best experts on this subject based on the ideXlab platform.

  • type zero Copper Proteins
    Nature Chemistry, 2009
    Co-Authors: Kyle M Lancaster, Serena Debeer George, John H Richards, Keiko Yokoyama, Harry B. Gray
    Abstract:

    Many Proteins contain Copper in a range of coordination environments, where it has various biological roles, such as transferring electrons or activating dioxygen. These Copper sites can be classified by their function or spectroscopic properties. Those with a single Copper atom are either type 1, with an intense absorption band near 600 nm, or type 2, with weak absorption in the visible region. We have built a novel Copper(ii) binding site within structurally modified Pseudomonas aeruginosa azurins that does not resemble either existing type, which we therefore call 'type zero'. X-ray crystallographic analysis shows that these sites adopt distorted tetrahedral geometries, with an unusually short Cu–O (G45 carbonyl) bond. Relatively weak absorption near 800 nm and narrow parallel hyperfine splittings in electron paramagnetic resonance spectra are the spectroscopic signatures of type zero Copper. Cyclic voltammetric experiments demonstrate that the electron transfer reactivities of type-zero azurins are enhanced relative to that of the corresponding type 2 (C112D) protein.

  • Encyclopedia of Inorganic and Bioinorganic Chemistry - Copper Proteins with Type 1 Sites
    Encyclopedia of Inorganic Chemistry, 2006
    Co-Authors: P. John Hart, Aram M Nersissian, Serena Debeer George
    Abstract:

    Copper Proteins with Type 1 Sites is a general review that focuses on single-domain Proteins that bind ‘blue’ or ‘type 1’ Copper. Larger, multidomain Proteins that contain type 1 Copper in addition to other types of Copper centers are not discussed at any length in this article. Blue Copper Proteins are so named because in solution they are a brilliant blue/azure color when the Copper ion is in its Cu(II) oxidation state. The bright blue color comes from a charge transfer (CT) between Cu(II) and the sulfur (thiolate) of a ligating cysteine residue. Because of this intense color, type 1 Copper Proteins were among the first to be isolated because they could be tracked easily during purification processes. This, together with their unique spectroscopic properties that have no parallel in small-molecule Copper complexes, has made them the subject of intense study over the last 35 years. This article focuses on three main aspects of type 1 Copper Proteins: (1) their occurrence, distribution, and classification based on analyses of genomic and expressed sequence tag data; (2) their three-dimensional structures as determined by the well-established tools of single-crystal X-ray diffraction and nuclear magnetic resonance (NMR); and (3) their electronic, spectroscopic, and electron-transfer properties. Keywords: type 1 Copper; blue Copper; X-ray crystallography; entatic state; electron paramagnetic resonance; resonance Raman; EXAFS/XAS; electron transfer; cupredoxins; phytocyanins