49 research outputs found
New Synthetic Routes for 1-Benzyl-1,4,7,10-tetraazacyclododecane and 1,4,7,10-Tetraazacyclododecane-1-acetic Acid Ethyl Ester, Important Starting Materials for Metal-coded DOTA-Based Affinity Tags
Two improved routes to synthesize 1-benzyl-1,4,7,10-tetraazacyclododecane (6) and 1,4,7,10- tetraazacyclododecane-1-acetic acid ethyl ester (11) are described as well as the synthesis of 1-{2-[4-(maleimido-N-propylacetamidobutyl)amino]-2-oxoethyl}-1,4,7,10-tetraazacyclododecane- 4,7,10-triacetic acid (17) and its Y, Ho, Tm, and Lu complexes. The 1H and 13C NMR spectra of the new compounds as well as the single crystal X-ray structure analyses of the intermediates 4-benzyl-1,7-bis(p-toluenesulfonyl)diethylenetriamine (3) and 1,4,7-tris(p-toluenesulfonyl)diethylenetriamine (7) are reported and discussed. The rare earth complexes of 17 have been characterized by 1H NMR spectroscopy and MALDI-TOF mass spectrometry.DFG, SPP 1166, Lanthanoidspezifische Funktionalitäten in Molekül und Materia
Working Principle of an Ionic Liquid Interlayer During Pressureless Lithium Stripping on LiAlLaZrO (LLZO) Garnet-Type Solid Electrolyte
Solid-state-batteries employing lithium metal anodes promise high theoretical energy and power densities. However, morphological instability occurring at the lithium/solid–electrolyte interface when stripping and plating lithium during cell cycling needs to be mitigated. Vacancy diffusion in lithium metal is not sufficiently fast to prevent pore formation at the interface above a certain current density during stripping. Applied pressure of several MPa can prevent pore formation, but this is not conducive to practical application. This work investigates the concept of ionic liquids as “self-adjusting” interlayers to compensate morphological changes of the lithium anode while avoiding the use of external pressure. A clear improvement of the lithium dissolution process is observed as it is possible to continuously strip more than 70 μm lithium (i. e., 15 mAh cm charge) without the need for external pressure during assembly and electrochemical testing of the system. The impedance of the investigated electrodes is analyzed in detail, and contributions of the different interfaces are evaluated. The conclusions are corroborated with morphology studies using cryo-FIB-SEM and chemical analysis using XPS. This improves the understanding of the impedance response and lithium stripping in electrodes employing liquid interlayers, acting as a stepping-stone for future optimization
The Intestinal Roundworm Ascaris suum Releases Antimicrobial Factors Which Interfere With Bacterial Growth and Biofilm Formation
Ascariasis is a widespread soil-transmitted helminth infection caused by the intestinal roundworm Ascaris lumbricoides in humans, and the closely related Ascaris suum in pigs. Progress has been made in understanding interactions between helminths and host immune cells, but less is known concerning the interactions of parasitic nematodes and the host microbiota. As the host microbiota represents the direct environment for intestinal helminths and thus a considerable challenge, we studied nematode products, including excretory-secretory products (ESP) and body fluid (BF), of A. suum to determine their antimicrobial activities. Antimicrobial activities against gram-positive and gram-negative bacterial strains were assessed by the radial diffusion assay, while effects on biofilm formation were assessed using the crystal violet static biofilm and macrocolony assays. In addition, bacterial neutralizing activity was studied by an agglutination assay. ESP from different A. suum life stages (in vitro-hatched L3, lung-stage L3, L4, and adult) as well as BF from adult males were analyzed by mass spectrometry. Several proteins and peptides with known and predicted roles in nematode immune defense were detected in ESP and BF samples, including members of A. suum antibacterial factors (ASABF) and cecropin antimicrobial peptide families, glycosyl hydrolase enzymes such as lysozyme, as well as c-type lectin domain-containing proteins. Native, unconcentrated nematode products from intestine-dwelling L4-stage larvae and adults displayed broad-spectrum antibacterial activity. Additionally, adult A. suum ESP interfered with biofilm formation by Escherichia coli, and caused bacterial agglutination. These results indicate that A. suum uses a variety of factors with broad-spectrum antibacterial activity to affirm itself within its microbe-rich environment in the gut
A cytosolic disulfide bridge‐supported dimerization is crucial for stability and cellular distribution of Coxsackievirus B3 protein 3A
RNA viruses in the Picornaviridae family express a large 250 kDa viral polyprotein that is processed by virus-encoded proteinases into mature functional proteins with specific functions for virus replication. One of these proteins is the highly conserved enteroviral transmembrane protein 3A that assists in reorganizing cellular membranes associated with the Golgi apparatus. Here, we studied the molecular properties of the Coxsackievirus B3 (CVB3) protein 3A with regard to its dimerization and its functional stability. By applying mutational analysis and biochemical characterization, we demonstrate that protein 3A forms DTT-sensitive disulfide-linked dimers via a conserved cytosolic cysteine residue at position 38 (Cys38). Homodimerization of CVB3 protein 3A via Cys38 leads to profound stabilization of the protein, whereas a C38A mutation promotes a rapid proteasome-dependent elimination of its monomeric form. The lysosomotropic agent chloroquine (CQ) exerted only minor stabilizing effects on the 3A monomer but resulted in enrichment of the homodimer. Our experimental data demonstrate that disulfide linkages via a highly conserved Cys-residue in enteroviral protein 3A have an important role in the dimerization of this viral protein, thereby preserving its stability and functional integrity
Extracellular proteasome-osteopontin circuit regulates cell migration with implications in multiple sclerosis
Osteopontin is a pleiotropic cytokine that is involved in several diseases
including multiple sclerosis. Secreted osteopontin is cleaved by few known
proteases, modulating its pro-inflammatory activities. Here we show by in
vitro experiments that secreted osteopontin can be processed by extracellular
proteasomes, thereby producing fragments with novel chemotactic activity.
Furthermore, osteopontin reduces the release of proteasomes in the
extracellular space. The latter phenomenon seems to occur in vivo in multiple
sclerosis, where it reflects the remission/relapse alternation. The
extracellular proteasome-mediated inflammatory pathway may represent a general
mechanism to control inflammation in inflammatory diseases
Orbital-driven Rashba effect in a binary honeycomb monolayer AgTe
The Rashba effect is fundamental to the physics of two-dimensional electron
systems and underlies a variety of spintronic phenomena. It has been proposed
that the formation of Rashba-type spin splittings originates microscopically
from the existence of orbital angular momentum (OAM) in the Bloch wave
functions. Here, we present detailed experimental evidence for this OAM-based
origin of the Rashba effect by angle-resolved photoemission (ARPES) and
two-photon photoemission (2PPE) experiments for a monolayer AgTe on Ag(111).
Using quantitative low-energy electron diffraction (LEED) analysis we determine
the structural parameters and the stacking of the honeycomb overlayer with
picometer precision. Based on an orbital-symmetry analysis in ARPES and
supported by first-principles calculations, we unequivocally relate the
presence and absence of Rashba-type spin splittings in different bands of AgTe
to the existence of OAM
A Helminth-Derived Chitinase Structurally Similar to Mammalian Chitinase Displays Immunomodulatory Properties in Inflammatory Lung Disease
From Hindawi via Jisc Publications RouterHistory: publication-year 2021, received 2021-09-02, accepted 2021-10-25, pub-print 2021-11-25, archival-date 2021-11-25Publication status: PublishedFunder: Coronado BiosciencesFunder: FAZIT Stiftung; doi: http://dx.doi.org/10.13039/501100003099Funder: Deutsche Forschungsgemeinschaft; doi: http://dx.doi.org/10.13039/501100001659; Grant(s): GRK 1673Immunomodulation of airway hyperreactivity by excretory-secretory (ES) products of the first larval stage (L1) of the gastrointestinal nematode Trichuris suis is reported by us and others. Here, we aimed to identify the proteins accounting for the modulatory effects of the T. suis L1 ES proteins and studied six selected T. suis L1 proteins for their immunomodulatory efficacy in a murine OVA-induced allergic airway disease model. In particular, an enzymatically active T. suis chitinase mediated amelioration of clinical signs of airway hyperreactivity, primarily associated with suppression of eosinophil recruitment into the lung, the associated chemokines, and increased numbers of RELMα+ interstitial lung macrophages. While there is no indication of T. suis chitinase directly interfering with dendritic cell activation or antigen presentation to CD4 T cells, treatment of allergic mice with the worm chitinase influenced the hosts’ own chitinase activity in the inflamed lung. The three-dimensional structure of the T. suis chitinase as determined by high-resolution X-ray crystallography revealed high similarities to mouse acidic mammalian chitinase (AMCase) but a unique ability of T. suis chitinase to form dimers. Our data indicate that the structural similarities between the parasite and host chitinase contribute to the disease-ameliorating effect of the helminth-derived chitinase on allergic lung inflammation
Rare earth element behaviour in seawater under the influence of organic matter cycling during a phytoplankton spring bloom – A mesocosm study
Rare earth elements (REEs) are used as powerful proxies for a variety of oceanic processes. The understanding of their biogeochemical behaviour in the marine environment is therefore essential. While the influence of OM-cycling on REE patterns in seawater is considered as insignificant, it has been shown that algae and bacteria provide good sorption surfaces for REEs and that components of the dissolved OM pool are able to complex REEs, thus potentially altering their behaviour. To investigate the impact of bio-associated processes on REEs in the bio-productive marine environment, we conducted an indoor mesocosm experiment that mimicked a phytoplankton spring bloom in the neritic coastal North Sea. The incubation period of 38 days covered two distinct phytoplankton bloom phases (diatoms followed by Phaeocystis sp.) and an interjacent bacterioplankton maximum. All dissolved REEs (dREEs) except samarium showed similar temporal concentration patterns, which were closely connected to the bloom succession. The concentration patterns were shaped by the ‘phytoplankton-shuttle’, which summarizes adsorption processes on phytoplankton-derived particulate OM (POM) and resulted in decreasing dREE concentrations alongside chlorophyll-a and POM maxima. The ‘heterotrophic-shuttle’ resulted in increasing dREE concentrations likely linked to heterotrophically mediated regeneration of POM and associated desorption processes. The effect of these processes on dREEs resulted in enhanced fractionation of light REEs (LREEs) relative to heavy REEs (HREEs) during adsorption processes and decreased fractionation as a result of desorption. At times of high dissolved organic carbon (DOC) concentrations, we observed a stabilization of especially dHREEs likely in organic complexes. To test the potential influence of DOC on dREEs, we used a PHREEQC model approach that revealed dREE complexation with components of the DOC pool and an increase in complexation with atomic mass of the REEs. That is, at high DOC concentrations OM-dREE complexation leads to an effective and preferential buffering of dHREE against adsorption. Our findings reveal that OM-cycling influences concentration patterns of dREEs via ad- and desorption processes as well as organic complexation with parts of the OM pool, suggesting these processes can have a significant impact on dREE concentrations in the natural marine environment under high OM conditions
The 20S Proteasome Splicing Activity Discovered by SpliceMet
The identification of proteasome-generated spliced peptides (PSP) revealed a new unpredicted activity of the major cellular protease. However, so far characterization of PSP was entirely dependent on the availability of patient-derived cytotoxic CD8+ T lymphocytes (CTL) thus preventing a systematic investigation of proteasome-catalyzed peptide splicing (PCPS). For an unrestricted PSP identification we here developed SpliceMet, combining the computer-based algorithm ProteaJ with in vitro proteasomal degradation assays and mass spectrometry. By applying SpliceMet for the analysis of proteasomal processing products of four different substrate polypeptides, derived from human tumor as well as viral antigens, we identified fifteen new spliced peptides generated by PCPS either by cis or from two separate substrate molecules, i.e., by trans splicing. Our data suggest that 20S proteasomes represent a molecular machine that, due to its catalytic and structural properties, facilitates the generation of spliced peptides, thereby providing a pool of qualitatively new peptides from which functionally relevant products may be selected