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Visar resultat 6 - 10 av 31 avhandlingar som matchar ovanstående sökkriterier.

  1. 6. Challenges in Enzyme Catalysis - Photosystem II and Orotidine Decarboxylase : A Density Functional Theory Treatment

    Författare :Marcus Lundberg; Margareta Blomberg; Per Siegbahn; Jeremy Harvey; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; photosystem II; oxyl radical; manganese systems; orotidine decarboxylase; reaction mechanism; density functional theory; Quantum chemistry; Kvantkemi;

    Sammanfattning : Possibly the most fascinating biochemical mechanism remaining to be solved is the formation of oxygen from water in photosystem II. This is a critical part of the photosynthetic reaction that makes solar energy accessible to living organisms. LÄS MER

  3. 7. Theoretical Modeling of Enzyme Catalysis with Focus on Radical Chemistry

    Författare :Vladimir Pelmenschikov; Per E. M. Siegbahn; Tim Clark; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; density functional theory; enzyme catalysis; radical chemistry; zinc-containing peptidase; methyl-coenzyme M reductase; ribonucleotide reductase; superoxide dismutase; Quantum chemistry; Kvantkemi;

    Sammanfattning : Hybrid density functional theory (DFT) B3LYP method is applied to study the four diverse enzyme systems: zinc-containing peptidases (thermolysin and stromelysin), methyl-coenzyme M reductase, ribonucleotide reductases (classes I and III), and superoxide dismutases (Cu,Zn- and Ni-dependent enzymes). Powerfull tools of modern quantum chemistry are used to address the questions of biological pathways at their molecular level, proposing a novel mechanism for methane production by methyl-coenzyme M reductase and providing additional insights into hydrolysis by zinc peptidases, substrate conversion by ribonucleotide reductases, and biological superoxide dismutation. LÄS MER

  4. 8. Luminescence properties of flexible conjugated dyes

    Författare :Jonas Sjöqvist; Patrick Norman; Mikael Lindgren; Jacob Kongsted; Linköpings universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; force field; molecular dynamics; linear absorption; QM MM; absorption spectrum; emission spectrum; water solvation; stokes shift;

    Sammanfattning : In this licentiate thesis the luminescence properties of two flexible conjugated dyes have been studied. The first, Pt1, is a platinum(II) acetylide chromophore used in optical power limiting materials. LÄS MER

  5. 9. Nitrile Hydratases and Epoxide-Transforming Enzymes : Quantum Chemical Modeling of Reaction Mechanisms and Selectivities

    Författare :Kathrin Hopmann; Fahmi Himo; Nigel G. Richards; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Biochemistry; Biokemi;

    Sammanfattning : Quantum chemical studies of enzymatic reactions are able to provide detailed insight into mechanisms and catalytic strategies. The energetic feasibility of proposed mechanisms can be established, and new possible reaction pathways can be put forward. LÄS MER

  7. 10. Theoretical Study of Vibronic Spectra of Molecule Systems Generated by Photo- and Electronic Excitations

    Författare :Ce Song; Yi Luo; Ying Zhang; KTH; []
    Nyckelord :Bioteknologi; Biotechnology;

    Sammanfattning : Spectra represent fingerprints of molecules, which contain unique information about their properties. Through analyzing the spectral data, one can reveal the molecules' energy level alignments, identify their species and geometric structures, and explore relevant chemical processes and microscopic mechanisms. LÄS MER