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    • Structure/function studies of the NAD<sup>+</sup>-dependent DNA ligase from the poly-extremophile Deinococcus radiodurans reveal importance of the BRCT domain for DNA binding 

      Fernandes, Andreia; Williamson, Adele Kim; Matias, Pedro M.; Moe, Elin (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-09-15)
      Bacterial NAD<sup>+</sup>-dependent DNA ligases (LigAs) are enzymes involved in replication, recombination, and DNA-repair processes by catalyzing the formation of phosphodiester bonds in the backbone of DNA. These multidomain proteins exhibit four modular domains, that are highly conserved across species, with the BRCT (breast cancer type 1 C-terminus) domain on the C-terminus of the enzyme. In ...

    • Sulfoxonium Ylide Derived Metal Carbenoids in Organic Synthesis 

      Vaitla, Janakiram; Bayer, Annette (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-12-12)
      As pioneered by Corey and Chaykovsky, sulfoxonium ylides have had widespread application in organic synthesis for more than a half century. In most of the reactions, sulfoxonium ylides were used to react with electrophiles. Under suitable reaction conditions these ylides can generate metal carbenoids and react with nucleophiles. By combining the typical reactivity of sulfoxonium ylides with ...

    • Supramolecular coronation of platinum(II) complexes by macrocycles: Structure, relativistic DFT calculations, and biological effects 

      Sojka, Martin; Chyba, Jan; Paul, Shib Shankar; Wawrocka, Karolina; Honigova, Katerina; Cuyacot, Ben Joseph R.; Castro, Abril C.; Vaculovic, Tomas; Marek, Jaromir; Repisky, Michal; Masarik, Michal; Novotny, Jan; Marek, Radek (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-11-05)
      Platinum-based anticancer drugs are actively developed utilizing lipophilic ligands or drug carriers for the efficient penetration of biomembranes, reduction of side effects, and tumor targeting. We report the development of a supramolecular host–guest system built on cationic platinum(II) compounds bearing ligands anchored in the cavity of the macrocyclic host. The host–guest binding and hydrolysis ...

    • Synergy between Experimental and Computational Approaches to Homogeneous Photoredox Catalysis 

      Demissie, Taye Beyene; Hansen, Jørn H (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-06-03)
      In this Frontiers article, we highlight how state-of-the-art density functional theory calculations can contribute to the field of homogeneous photoredox catalysis. We discuss challenges in the fields and potential solutions to be found at the interface between theory and experiment. The exciting opportunities and insights that can arise through such an interdisciplinary approach are highlighted.

    • A Synergy of Artificial Bee Colony and Genetic Algorithms to Determine the Parameters of the Σ-Gram Distance 

      Muhammad Fuad, Muhammad Marwan (Journal article; Tidsskriftartikkel; Peer reviewed, 2014)
      In a previous work we presented the Σ-gram distance that computes the similarity between two sequences. This distance includes parameters that we calculated by means of an optimization process using artificial bee colony. In another work we showed how population-based bio-inspired algorithms can be sped up by applying a method that utilizes a pre-initialization stage to yield an optimal initial ...

    • Synthesis and biological evaluation of new dipicolylamine zinc chelators as metallo-β-lactamase inhibitors 

      Prandina, Anthony; Radix, Sylvie; Le Borgne, Marc; Jordheim, Lars Petter; Bousfiha, Zineb; Fröhlich, Christopher; Leiros, Hanna-Kirsti S.; Samuelsen, Ørjan; Frøvold, Espen; Rongved, Pål; Åstrand, Ove Alexander Høgmoen (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-02-02)
      Antibiotics are key drugs in modern healthcare, especially in hospitals, where multiresistant bacteria resides and is a potential threat to human health. In the present work, a new series of adjuvants working synergistically with the carbapenem meropenem, in which a selective zinc-chelating agent was covalently linked to the small bacterial peptide D-Ala-D-Ala, was synthesized and tested against ...

    • Synthesis and Molecular Structure of a Copper Octaiodocorrole 

      Thomassen, Ivar Kristian; McCormick, Laura J.; Ghosh, Abhik (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-05-09)
      Although rather delicate on account of their propensity to undergo deiodination, β-octaiodoporphyrinoids are of considerable interest as potential precursors to novel β-octasubstituted macrocycles. Presented herein are early results of our efforts to synthesize β-octaiodocorrole derivatives. Oxidative condensation of 3,4-diiodopyrrole and aromatic aldehydes failed to yield free-base octaiodocorroles. ...

    • Synthesis and molecular structure of perhalogenated rhenium-oxo corroles 

      Alemayehu, Abraham B.; Einrem, Rune F.; McCormick‑McPherson, Laura J.; Settineri, Nicholas S.; Ghosh, Abhik (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-11-12)
      As part of our efforts to develop rhenium-oxo corroles as photosensitizers for oxygen sensing and photodynamic therapy, we investigated the potential <i>β</i>-perhalogenation of five ReO <i>meso</i>-tris(<i>para</i>-X-phenyl)corroles, Re[T<i>p</i>XPC](O) (X = CF<sub>3</sub>, H, F, CH<sub>3</sub>, and OCH<sub>3</sub>), with elemental chlorine and bromine. With Cl<sub>2</sub>, <i>β</i>-octachlorinated ...

    • Synthesis of 5,7-diarylindoles via Suzuki-Miyaura coupling in water 

      Elumalai, Vijayaragavan; Hansen, Jørn H (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-11-16)
      The synthesis of novel 5,7-diaryl and diheteroaryl indoles has been explored via efficient double Suzuki–Miyaura coupling. The method notably employs a low catalyst loading of Pd(PPh<sub>3</sub>)<sub>4</sub> (1.5 mol%/coupling) and water as the reaction solvent to obtain 5,7-diarylated indoles without using N-protecting groups in up to 91% yield. The approach is also suitable for N-protected and ...

    • Synthesis of Indoles and Pyrroles Utilizing Iridium Carbenes Generated from Sulfoxonium Ylides 

      Vaitla, Janakiram; Bayer, Annette; Hopmann, Kathrin Helen (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-03-20)
      Metal carbenes can undergo a myriad of synthetic transformations. Sulfur ylides are potential safe precursors of metal carbenes. Herein, we report cascade reactions that involve carbenoids derived from sulfoxonium ylides for the efficient and regioselective synthesis of indoles and pyrroles. The tandem action of iridium and Brønsted acid catalysts enables rapid assembly of the heterocycles from ...

    • Synthesis, Spectroscopy, Electrochemistry and DFT of Electron-Rich Ferrocenylsubphthalocyanines 

      Conradie, Jeanet; Swarts, Petrus (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-01)
      A series of novel ferrocenylsubphthalocyanine dyads Y-BSubPc(H)<sub>12</sub> with ferrocenylcarboxylic acids Y-H = (FcCH<sub>2</sub>CO<sub>2</sub>-H), (Fc(CH<sub>2</sub>)<sub>3</sub>CO<sub>2</sub>-H) or (FcCO(CH<sub>2</sub>)<sub>2</sub>CO<sub>2</sub>-H) in the axial position were synthesized from the parent Cl-BSubPc(H)<sub>12</sub> via an activated triflate-SubPc intermediate. UV/Vis data revealed ...

    • Synthetic analogs of stryphnusin isolated from the marine sponge Stryphnus fortis inhibit acetylcholinesterase with no effect on muscle function or neuromuscular transmission 

      Moodie, Lindon; Zuzek, Monika; Frangez, Robert; Andersen, Jeanette hammer; Hansen, Espen; Olsen, Elisabeth Klungerbo; Cergolj, Marija; Sepcic, Kristina; Hanssen, Kine Østnes; Svenson, Johan (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-11-09)
      The marine secondary metabolite stryphnusin (1) was isolated from the boreal sponge Stryphnus fortis, collected off the Norwegian coast. Given its resemblance to other natural acetylcholinesterase antagonists, it was evaluated against electric eel acetylcholinesterase and displayed inhibitory activity. A library of twelve synthetic phenethylamine analogs, 2a–7a and 2b–7b, containing tertiary and ...

    • Synthetic cationic antimicrobial peptides bind with their hydrophobic parts to drug site II of human serum albumin 

      Sivertsen, Annfrid; Isaksson, Johan; Leiros, Hanna-Kirsti S.; Svenson, Johan; Svendsen, John Sigurd; Brandsdal, Bjørn Olav (Journal article; Tidsskriftartikkel; Peer reviewed, 2014)

    • A Synthetic Route to Quaternary Pyridinium Salt-Functionalized Silsesquioxanes 

      Kostenko, Nataliya; Gottfriedsen, Jochen; Hilfert, Liane; Edelmann, Frank T (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)
      A synthetic route to potentially biocidal silsesquioxanes functionalized by quaternary pyridinium functionalities has been developed. N-Alkylation reactions of the precursor compounds 4-(2-(trimethoxysilyl)ethyl)-pyridine (5) and 4-(2-trichloro-silylethyl)pyridine (6) with iodomethane, n-hexylbromide, and n-hexadecylbromide cleanly afforded the corresponding N-alkylpyridinium salts (7–10). The ...

    • Tailored Leaching Tests as a Tool for Environmental Management of Mine Tailings Disposal at Sea 

      Pedersen, Kristine B.; Lejon, Tore; Evenset, Anita (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-03-10)
      The expanding human activities in coastal areas increase the need for developing solutions to limit impacts on the marine environment. Sea disposal affects the marine environment, but despite the growing knowledge of potential impacts, there are still no standardized leaching tests for sea disposal. The aim of this study was to contribute to the development of leaching tests, exemplified using ...

    • Temperature adaptation of DNA ligases from psychrophilic organisms 

      Berg, Kristel; Leiros, Ingar; Williamson, Adele Kim (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-03-02)
      DNA ligases operating at low temperatures have potential advantages for use in biotechnological applications. For this reason, we have characterized the temperature optima and thermal stabilities of three minimal Lig E-type ATP-dependent DNA ligase originating from Gram-negative obligate psychrophilic bacteria. The three ligases, denoted Vib-Lig, Psy-Lig, and Par-Lig, show a remarkable range of ...

    • Temporal dynamics of intra-and extra-cellular microcystins concentrations in Koka reservoir (Ethiopia): Implications for public health risk 

      Tilahun, Samson; Kifle, Demeke; Zewde, Tigist W; Johansen, Jostein a; Demissie, Taye Beyene; Hansen, Jørn H (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-06-20)
      This study was carried out with a view of understanding the temporal dynamics of microcystin concentrations in both algal seston and water samples and the associated public health risk. All the major MC variants, namely MC-LR, MC-YR, and MC-RR, were detected in both the algal seston and water samples. In the majority of the samples, the most potent variant, MC-LR, constituted the greatest proportion ...

    • Theoretical Analysis of NMR Shieldings in XSe and XTe (X= Si, Ge, Sn and Pb): The Spin–Rotation Constant Saga 

      Demissie, Taye Beyene (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-12-21)
      The nuclear spin-rotation (NSR) and absolute nuclear magnetic resonance (NMR) shielding tensors of the nuclei in the series of X<sup>77</sup>Se and X<sup>125</sup>Te (X = <sup>29</sup>Si, <sup>73</sup>Ge, <sup>119</sup>Sn and <sup>207</sup>Pb) are calculated using fourcomponent relativistic density functional theory (DFT) and coupled-cluster singles-doubles with a perturbative triples correction ...

    • Theoretical Photoelectron Spectroscopy of Low-Valent Carbon Species: A ∼6 eV Range of Ionization Potentials among Carbenes, Ylides, and Carbodiphosphoranes 

      Ghosh, Abhik; Conradie, Jeanet (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-12-02)
      High-quality density functional theory calculations underscore a nearly 6 eV range for the ionization potentials (IPs) of neutral, low-valent carbon compounds, including carbenes, ylides, and zero-valent carbon compounds (carbones) such as carbodiphosphoranes (CDPs) and carbodicarbenes. Thus, adiabatic IPs as low as 5.5 ± 0.1 eV are predicted for CDPs, which are about 0.7–1.2 eV lower than those of ...

    • A Theoretical Search for Stable Terminal Carbides 

      Ghosh, Abhik; Conradie, Jeanet (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-11-20)
      xploratory scalar-relativistic density functional theory (B3LYP*-D3/ZORA-STO-TZ2P) calculations have been used to examine the stability and bonding of pseudotetrahedral Group 8 (Fe, Ru, and Os) and Group 9 (Co, Rh, and Ir) terminal carbide complexes with dδ4 ground states and tripodal tris(N-heterocyclic-carbene) supporting ligands. The calculations predict relatively low adiabatic ionization ...