Sökning: "Per E.M. Siegbahn"

Visar resultat 1 - 5 av 6 avhandlingar innehållade orden Per E.M. Siegbahn.

  1. 1. Biomimetic Transition Metal Catalysts : Insights from Theoretical Modeling

    Författare :Adam Johannes Johansson; Per E. M. Siegbahn; Margareta R. A. Blomberg; Per-Ola Norrby; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Catalysis; biomimetic; copper; non-heme iron; heme iron; O2 cleavage; H-atom transfer; radical chemistry; redox chemistry; thermo chemistry; entropy calculations; quantum chemistry; spin states; density functional theory DFT ; self-interaction error SIE .; Chemical physics; Kemisk fysik; kemisk fysik; Chemical Physics;

    Sammanfattning : The scientific interest in the chemistry of synthetic transition metal complexes is motivated by at least two arguments:1.These can be regarded as models of biological transition metal complexes, e.g. metalloenzymes, whose functions can be difficult to reveal in detail due to their complexity. LÄS MER

  3. 2. Theoretical studies of mononuclear non-heme iron active sites

    Författare :Arianna Bassan; Per E. M. Siegbahn; Sason Shaik; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; quantum chemistry; enzyme catalysis; iron enzymes; Quantum chemistry; Kvantkemi;

    Sammanfattning : The quantum chemical investigations presented in this thesis use hybrid density functional theory to shed light on the catalytic mechanisms of mononuclear non-heme iron oxygenases, accommodating a ferrous ion in their active sites. More specifically, the dioxygen activation process and the subsequent oxidative reactions in the following enzymes were studied: tetrahydrobiopterin-dependent hydroxylases, naphthalene 1,2-dioxygenase and α-ketoglutarate-dependent enzymes. LÄS MER

  4. 3. Reaction Mechanisms of Metalloenzymes and Synthetic Model Complexes Activating Dioxygen : A Computational study

    Författare :Valentin Georgiev; Per E.M. Siegbahn; Sam de Visser; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; catalysis; density functional theory; extradiol; intradiol; dioxygenases; oxygen; biomimetic complexes; heme; spin transition; adipic acid; Chemical physics; Kemisk fysik; kvantkemi; Quantum Chemistry;

    Sammanfattning : Quantum chemistry has nowadays become a powerful and efficient tool that can be successfully used for studies of biosystems. It is therefore possibleto model the enzyme active-site and the reactions undergoing into it, as well as obtaining quite accurate energetic profiles. LÄS MER

  5. 4. Calculations of Reaction Mechanisms and Entropic Effects in Enzyme Catalysis

    Författare :Masoud Kazemi; Johan Åqvist; Per E. M. Siegbahn; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Enzyme catalysis; Entropy; Cytidine deamination; Ribosome; Peptidyl-tRNA hydrolysis; Peptide bond formation; Empirical valence bond method; Density functional theory; Biology with specialization in Structural Biology; Biologi med inriktning mot strukturbiologi; Biokemi; Biochemistry; Biology with specialization in Molecular Biotechnology; Biologi med inriktning mot molekylär bioteknik;

    Sammanfattning : Ground state destabilization is a hypothesis to explain enzyme catalysis. The most popular interpretation of it is the entropic effect, which states that enzymes accelerate biochemical reactions by bringing the reactants to a favorable position and orientation and the entropy cost of this is compensated by enthalpy of binding. LÄS MER

  7. 5. Biomimetic Iron Complexes involved in Oxygenation and Chlorination : A Theoretical Study

    Författare :Holger Noack; Margareta R. A. Blomberg; Per E. M. Siegbahn; Martin Kaupp; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; biomimetic; iron; density functional theory; intradiol; chlorination; adpic acid; diamond core; reactivity; Bio-inorganic chemistry; Bio-oorganisk kemi; Theoretical chemistry; Teoretisk kemi; kemisk fysik; Chemical Physics;

    Sammanfattning : Biomimetic chemistry is directed towards the simulation of enzymatic reactivity with synthetic analogues. In this thesis a quantum chemical method has been employed to study the mechanism of highly reactive iron-oxo complexes involved in oxygenation and chlorination of organic substrates. LÄS MER