Institutt for kjemi: Recent submissions
Now showing items 61-80 of 611
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Raman spectroscopy online monitoring of biomass production, intracellular metabolites and carbon substrates during submerged fermentation of oleaginous and carotenogenic microorganisms
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-12-18)Background - Monitoring and control of both growth media and microbial biomass is extremely important for the development of economical bioprocesses. Unfortunately, process monitoring is still dependent on a limited number of standard parameters (pH, temperature, gasses etc.), while the critical process parameters, such as biomass, product and substrate concentrations, are rarely assessable in-line. ... -
Radical Group Transfer of Vinyl and Alkynyl Silanes Driven by Photoredox Catalysis
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-08-15)Radical group transfer is a powerful tool for the formation of C−C bonds. These processes typically involve radical addition to C−C π bonds, followed by fragmentation of the resulting cyclic intermediate. Despite the advantageous lability of organosilanes in this context, silicon-tethered radical acceptor groups have remained underexplored in radical group transfer reactions. We report a general ... -
Free-Base Corrole Anion
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-08-30)Free-base corroles have long been known to be acidic, readily undergoing deprotonation by mild bases and in polar solvents. The conjugate base, however, has not been structurally characterized until now. Presented here is a first crystal structure of a freebase corrole anion, derived from tris(p-cyanophenyl)corrole, as the tetrabuylammonium salt. The low-temperature (100 K) structure reveals ... -
FAIR+E pathogen data for surveillance and research: lessons from COVID-19
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-11-21)The COVID-19 pandemic has exemplified the importance of interoperable and equitable data sharing for global surveillance and to support research. While many challenges could be overcome, at least in some countries, many hurdles within the organizational, scientific, technical and cultural realms still remain to be tackled to be prepared for future threats. We propose to (i) continue supporting global ... -
Jahn-Teller distortion in bis(terpyridine)nickel(III) – Elongation or compression?
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-11-06)DFT methods were used to evaluate the type of Jahn-Teller distortion in the low spin d<sup>7</sup> bis(terpyridine)nickel (III) doublet. The strain of the tridentate terpyridine ligand in bis(terpyridine)nickel(III) leads to longer Ni(III)-N terminal bond lengths than the Ni(III)-N central bonds. In addition, in all DFT optimized bis(terpyridine)nickel (III) molecules, the one set of Ni(III)-N ... -
Constrained DFT-based magnetic machine-learning potentials for magnetic alloys: a case study of Fe–Al
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-11-13)We propose a machine-learning interatomic potential for multi-component magnetic materials. In this potential we consider magnetic moments as degrees of freedom (features) along with atomic positions, atomic types, and lattice vectors. We create a training set with constrained DFT (cDFT) that allows us to calculate energies of confgurations with non-equilibrium (excited) magnetic moments and, ... -
Towards high-throughput screening (HTS) of polyhydroxyalkanoate (PHA) production via Fourier transform infrared (FTIR) spectroscopy of Halomonas sp. R5-57 and Pseudomonas sp. MR4-99
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-03-08) -
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 ...