131 research outputs found
X-ray crystallographic structure of a papain-leupeptin complex
AbstractThe three-dimensional structure of the papain-leupeptin complex has been determined by X-ray crystallography to a resolution of 2.1 Ă
(overall R-factor = 19.8%). The structure indicates that: (i) leupeptin contacts the S subsites of the papain active site and not the S'subsites; (ii) the âcarbonylâ carbon atom of the inhibitor is covalently bound by the Cys-25 sulphur atom of papain and is tetrahedrally coordinated; (iii) the âcarbonylâ oxygen atom of the inhibitor faces the oxyanion hole and makes hydrogen bond contacts with Gln-19 and Cys-25
Zukunftsbild Hochschullehre 2025
Das Diskussionspapier zur Hochschullehre 2025 zeichnet sich methodisch durch seine partizipative Entstehung aus: In einem der HFDcon 2022 zeitlich vorgelagerten Prozess trafen sich 21 angemeldete Teilnehmer:innen aus dem deutschen Hoch- schulumfeld, um den Wandel der Hochschullehre fĂŒr das Jahr 2025 zu skizzieren und Thesen fĂŒr eine neue Denkkultur zu formu- lieren.
In mehreren virtuellen Sitzungen wurden zunĂ€chst die Ziele des Papiers definiert, Themen geclustert und erste Forderungen ent- wickelt. Innerhalb der folgenden vier Wochen wurde dann â teils in Kleingruppen â kontrovers diskutiert, formuliert und ĂŒberarbeitet, bis das Papier am 30. Juni 2022 in seiner ersten Fassung auf der Konferenz HFDcon 2022 vorgestellt wurde
Molecular behaviour of phenol in zeolite Beta catalysts as a function of acid site presence: a quasielastic neutron scattering and molecular dynamics simulation study
Quasielastic neutron scattering (QENS) experiments complemented by classical molecular dynamics (MD) simulations at 393â443 K were employed in a study of the mobility and interactions of phenol in acidic zeolite H-Beta, to understand systems relevant to potential routes for the depolymerization and hydrodeoxygenation of lignin. QENS experiments observed isotropic phenol rotation with a fraction of static molecules, yielding rotational diffusion coefficients between 2.60 Ă 1010 and 3.33 Ă 1010 sâ1 and an activation energy of rotation of 7.2 kJ molâ1. The MD simulations of phenol in the acidic and all-silica zeolite corroborate the experimental results, where molecules strongly adsorbed to the acidic sites behave as an immobile fraction with minimal contribution to the rotational diffusion, and the mobile molecules yield similar rotational diffusion coefficients to experiment. Translational diffusion is too slow to be detected in the instrumental time window of the QENS experiments, which is supported by MD-calculated activation energies of translation larger than 25 kJ molâ1. The study illustrates the effect of active sites in potential catalyst structures on the dynamical behaviour of molecules relevant to biomass conversion
EURECâŽA
The science guiding the EURECâŽA campaign and its measurements is presented. EURECâŽA comprised roughly 5 weeks of measurements in the downstream winter trades of the North Atlantic â eastward and southeastward of Barbados. Through its ability to characterize processes operating across a wide range of scales, EURECâŽA marked a turning point in our ability to observationally study factors influencing clouds in the trades, how they will respond to warming, and their link to other components of the earth system, such as upper-ocean processes or the life cycle of particulate matter. This characterization was made possible by thousands (2500) of sondes distributed to measure circulations on meso- (200âkm) and larger (500âkm) scales, roughly 400âh of flight time by four heavily instrumented research aircraft; four global-class research vessels; an advanced ground-based cloud observatory; scores of autonomous observing platforms operating in the upper ocean (nearly 10â000 profiles), lower atmosphere (continuous profiling), and along the airâsea interface; a network of water stable isotopologue measurements; targeted tasking of satellite remote sensing; and modeling with a new generation of weather and climate models. In addition to providing an outline of the novel measurements and their composition into a unified and coordinated campaign, the six distinct scientific facets that EURECâŽA explored â from North Brazil Current rings to turbulence-induced clustering of cloud droplets and its influence on warm-rain formation â are presented along with an overview of EURECâŽA's outreach activities, environmental impact, and guidelines for scientific practice. Track data for all platforms are standardized and accessible at https://doi.org/10.25326/165 (Stevens, 2021), and a film documenting the campaign is provided as a video supplement
EURECâŽA
The science guiding the EURECâŽA campaign and its measurements is presented. EURECâŽA comprised roughly 5 weeks of measurements in the downstream winter trades of the North Atlantic â eastward and southeastward of Barbados. Through its ability to characterize processes operating across a wide range of scales, EURECâŽA marked a turning point in our ability to observationally study factors influencing clouds in the trades, how they will respond to warming, and their link to other components of the earth system, such as upper-ocean processes or the life cycle of particulate matter. This characterization was made possible by thousands (2500) of sondes distributed to measure circulations on meso- (200âkm) and larger (500âkm) scales, roughly 400âh of flight time by four heavily instrumented research aircraft; four global-class research vessels; an advanced ground-based cloud observatory; scores of autonomous observing platforms operating in the upper ocean (nearly 10â000 profiles), lower atmosphere (continuous profiling), and along the airâsea interface; a network of water stable isotopologue measurements; targeted tasking of satellite remote sensing; and modeling with a new generation of weather and climate models. In addition to providing an outline of the novel measurements and their composition into a unified and coordinated campaign, the six distinct scientific facets that EURECâŽA explored â from North Brazil Current rings to turbulence-induced clustering of cloud droplets and its influence on warm-rain formation â are presented along with an overview of EURECâŽA's outreach activities, environmental impact, and guidelines for scientific practice. Track data for all platforms are standardized and accessible at https://doi.org/10.25326/165 (Stevens, 2021), and a film documenting the campaign is provided as a video supplement
Cardiac peroxiredoxins undergo complex modifications during cardiac oxidant stress
Peroxiredoxins (Prdxs), a family of antioxidant and redox-signaling proteins, are plentiful within the heart; however, their cardiac functions are poorly understood. These studies were designed to characterize the complex changes in Prdxs induced by oxidant stress in rat myocardium. Hydrogen peroxide, a Prdx substrate, was used as the model oxidant pertinent to redox signaling during health and to injury at higher concentrations. Rat hearts were aerobically perfused with a broad concentration range of hydrogen peroxide by the Langendorff method, homogenized, and analyzed by immunoblotting. Heart extracts were also analyzed by size-exclusion chromatography under nondenaturing conditions. Hydrogen peroxide-induced changes in disulfide bond formation, nonreversible oxidation of cysteine (hyperoxidation), and subcellular localization were determined. Hydrogen peroxide induced an array of changes in the myocardium, including formation of disulfide bonds that were intermolecular for Prdx1, Prdx2, and Prdx3 but intramolecular within Prdx5. For Prdx1, Prdx2, and Prdx5, disulfide bond formation can be approximated to an EC50 of 10â100, 1â10, and 100â1,000 ÎŒM peroxide, respectively. Hydrogen peroxide induced hyperoxidation, not just within monomeric Prdx (by SDS-PAGE), but also within Prdx disulfide dimers, and reflects a flexibility within the dimeric unit. Prdx oxidation was also associated with movement from the cytosolic to the membrane and myofilament-enriched fractions. In summary, Prdxs undergo a complex series of redox-dependent structural changes in the heart in response to oxidant challenge with its substrate hydrogen peroxide
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