Artikler, rapporter og annet (kjemi): Recent submissions
Now showing items 61-80 of 551
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Bulky, electron-rich, renewable: analogues of Beller's phosphine for cross-couplings
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-10-30)In recent years, considerable progress has been made in the conversion of biomass into renewable chemicals, yet the range of value-added products that can be formed from biomass remains relatively small. Herein, we demonstrate that molecules available from biomass serve as viable starting materials for the synthesis of phosphine ligands, which can be used in homogeneous catalysis. Specifically, ... -
Influence of Fluorinated Substituents on the Near-Infrared Phosphorescence of 5d Metallocorroles
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-07-12)The influence of fluorinated substituents on the luminescent properties of rhenium-oxo, osmium-nitrido, and gold triarylcorroles was studied via a comparison of four ligands: triphenylcorrole (TPC), tris(ptrifluoromethylphenyl)corrole (TpCF<sub>3</sub>PC), tris{3,5-bis(trifluoromethyl)- phenyl}corrole (T3,5-CF<sub>3</sub>PC), and tris(pentafluorophenyl)corrole (TPFPC). For each metal series ... -
Initial characterization of an iron superoxide dismutase from Thermobifida fusca
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-09-19)Superoxide dismutases (SODs) are enzymes that catalyze the dismutation of the superoxide radical anion into O<sup>2</sup> and H<sup>2</sup>O<sup>2</sup> in a two-step reaction. They are ubiquitous to all forms of life and four different types of metal centers are detected, dividing this class of enzymes into Cu-/Zn-, Ni-, Mn-, and Fe-SODs. In this study, a superoxide dismutase from the ... -
Insights into the role of three Endonuclease III enzymes for oxidative stress resistance in the extremely radiation resistant bacterium Deinococcus radiodurans
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-09-12)The extremely radiation and desiccation resistant bacterium Deinococcus radiodurans possesses three genes encoding Endonuclease III-like enzymes (DrEndoIII1, DrEndoIII2, DrEndoIII3). In vitro enzymatic activity measurements revealed that DrEndoIII2 is the main Endonuclease III in this organism, while DrEndoIII1 and 3 possess unusual and, so far, no detectable EndoIII activity, respectively. In ... -
Cost-Efficient High-Resolution Linear Absorption Spectra Through Extrapolating the Dipole Moment from Real-Time Time-Dependent Electronic-Structure Theory
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023)We present a novel function fitting method for approximating the propagation of the time-dependent electric dipole moment from real-time electronic structure calculations. Real-time calculations of the electronic absorption spectrum require discrete Fourier transforms of the electric dipole moment. The spectral resolution is determined by the total propagation time, i.e. the trajectory length of the ... -
2.09 Å resolution structure of E. coli HigBA toxin-antitoxin complex reveals an ordered DNA-binding domain and intrinsic dynamics in antitoxin
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-10-29)The toxin–antitoxin (TA) systems are small operon systems that are involved in important physiological processes in bacteria such as stress response and persister cell formation. Escherichia coli HigBA complex belongs to the type II TA systems and consists of a protein toxin called HigB and a protein antitoxin called HigA. The toxin HigB is a ribosome-dependent endoribonuclease that cleaves the ... -
Lateral membrane organization as target of an antimicrobial peptidomimetic compound
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-07-07)Antimicrobial resistance is one of the leading concerns in medical care. Here we study the mechanism of action of an antimicrobial cationic tripeptide, AMC-109, by combining high speed-atomic force microscopy, molecular dynamics, fluorescence assays, and lipidomic analysis. We show that AMC-109 activity on negatively charged membranes derived from Staphylococcus aureus consists of two crucial steps. ... -
Arctic, marine bacteria and their ability to produce polyhydroxyalkonates (PHAs) using underexploited biomass as nutrient source
(Conference object; Konferansebidrag, 2017)<p>In this project we are studying marine bacteria and their ability to produce polyhydroxyalkonates (PHAs), a fully biodegradable polyester known as bioplastic. Bioplastics can replace petroleum-based plastics in many applications. PHAs accumulate as intracellular carbon and energy storages when the bacteria grow in an environment with nutrient imbalance. The monomeric building blocks in the PHA ... -
Arctic marine bacteria for bioplastic production
(Conference object; Konferansebidrag, 2018)<p>Oil-based plastic production now exceeds 330 Mt annually1 and poses a major environmental problem. Polyhydroxyalkanoates (PHA) is a group of bioplastic polyesters that can replace oil-based plastics in many applications, but economic costs are higher and industrial-scale production still limited. PHA is produced naturally by diverse groups of bacteria and stored intracellularly as hydrophobic ... -
Polarizable Density Embedding for Large Biomolecular Systems
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-09-29)We present an efficient and robust fragment-based quantum–classical embedding model capable of accurately capturing effects from complex environments such as proteins and nucleic acids. This is realized by combining the molecular fractionation with conjugate caps (MFCC) procedure with the polarizable density embedding (PDE) model at the level of Fock matrix construction. The PDE contributions to the ... -
Computational design of the temperature optimum of an enzyme reaction
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-06-28)Cold-adapted enzymes are characterized both by a higher catalytic activity at low temperatures and by having their temperature optimum down-shifted, compared to mesophilic orthologs. In several cases, the optimum does not coincide with the onset of protein melting but reflects some other type of inactivation. In the psychrophilic α-amylase from an Antarctic bacterium, the inactivation is thought to ... -
Comparative study of CO2 insertion into pincer supported palladium alkyl and aryl complexes
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-07-12)The insertion of CO2 into metal alkyl bonds is a crucial elementary step in transition metal-catalyzed processes for CO2 utilization. Here, we synthesize pincer-supported palladium complexes of the type (tBuPBP)Pd(alkyl) (tBuPBP = B(NCH2PtBu2)2C6H4−; alkyl = CH2CH3, CH2CH2CH3, CH2C6H5, and CH2-4-OMe-C6H4) and (tBuPBP)Pd(C6H5) and compare the rates of CO2 insertion into the palladium alkyl bonds to ... -
B12 and F430 models: Metal- versus ligand-centered redox in cobalt and nickel tetradehydrocorrin derivatives
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-03-23)DFT calculations with the well-tested OLYP and B3LYP* exchange-correlation functionals (along with D3 dispersion corrections and all-electron ZORA STO-TZ2P basis sets) and careful use of group theory have led to significant insights into the question of metal- versus ligand-centered redox in Co and Ni B,C-tetradehydrocorrin complexes. For the cationic complexes, both metals occur in their low-spin ... -
Gruppelærerdagen – undervisningskvalitet fra første time
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-25)Ved norske universiteter er det vanlig at stipendiater eller studenter fra tidligere kull utfører en stor del av undervisningen innen realfagene. Fokus på opplæring av denne gruppen undervisere kan bidra til en positiv effekt på undervisningskvalitet og studentenes læring. Det varierer imidlertid fra institusjon til institusjon om det finnes en slik type opplæring, og omfang og kvalitet på ... -
Rhenium Biscorrole Sandwich Compounds: XAS Evidence for a New Coordination Motif
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-05-23)The interaction of three free-base meso-tris(p-X-phenyl)corroles H3[TpXPC] (X = H, CH3, OCH3) with Re2(CO)10 at 235 °C in the presence of K2CO3 in o-dichlorobenzene has led to putative rhenium biscorrole sandwich compounds with the formula ReH[TpXPC]2. Density functional theory calculations and Re L3-edge extended X-ray absorption fine structure measurements suggest a seven-coordinate metal center, ... -
The Perfluoro Cage Effect: A Search for Electron-Encapsulating Molecules
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-01-25)Quantum chemical calculations have for some time predicted that perfluorinated polyhedral organic molecules should exhibit a low-energy LUMO consisting of the overlapping inward-pointing lobes of the C−F σ* orbitals. Accordingly, these molecules should be able to encapsulate an electron within the interior of their cavities. Inspired by the recent confirmation of this prediction for perfluorocubane, ... -
Lignocellulose Conversion via Catalytic Transformations Yields Methoxyterephthalic Acid Directly from Sawdust
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-10)Poly(ethylene terephthalate) polyester represents the most common class of thermoplastic polymers widely used in the textile, bottling, and packaging industries. Terephthalic acid and ethylene glycol, both of petrochemical origin, are polymerized to yield the polyester. However, an earlier report suggests that polymerization of methoxyterephthalic acid with ethylene glycol provides a methoxy-polyester ... -
Investigation of tetrasubstituted heterocycles reveals hydantoins as a promising scaffold for development of novel antimicrobials with membranolytic properties
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-01-24)Mimics of antimicrobial peptides (AMPs) have been proposed as a promising class of antimicrobial agents. We report the analysis of five tetrasubstituted, cationic, amphipathic heterocycles as potential AMP mimics. The analysis showed that the heterocyclic scaffold had a strong influence on the haemolytic activity of the compounds, and the hydantoin scaffold was identified as a promising template for ... -
Contrasting the phospholipid profiles of two neoplastic cell lines reveal a high PC:PE ratio for SH-SY5Y cells relative to A431 cells
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-03-14)Lipids have been implicated in Parkinson's Disease (PD). We therefore studied the lipid profile of the neuroblastoma SH-SY5Y cell line, which is used extensively in PD research and compared it to that of the A431 epithelial cancer cell line. We have isolated whole cell extracts (WC) and plasma membrane (PM) fractions of both cell lines. The isolates were analyzed with 31P NMR. We observed a significant ... -
Biochemical and structural characterisation of a family GH5 cellulase from endosymbiont of shipworm P. megotara
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-04)Background Cellulases play a key role in the enzymatic conversion of plant cell-wall polysaccharides into simple and economically relevant sugars. Thus, the discovery of novel cellulases from exotic biological niches is of great interest as they may present properties that are valuable in the biorefning of lignocellulosic biomass. Results We have characterized a glycoside hydrolase 5 (GH5) domain ...