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11.
Alexander Boldt Jan Walter Fabian Hofbauer Karen Stetter Ines Aubel Martin Bertau Christof M. Jäger Thomas Walther 《Engineering in Life Science》2023,23(3):e202200052
The recovery and valorization of metals and rare earth metals from wastewater are of great importance to prevent environmental pollution and recover valuable resources. Certain bacterial and fungal species are capable of removing metal ions from the environment by facilitating their reduction and precipitation. Even though the phenomenon is well documented, little is known about the mechanism. Therefore, we systematically investigated the influence of nitrogen sources, cultivation time, biomass, and protein concentration on silver reduction capacities of cell-free cultivation media (spent media) of Aspergillus niger, A. terreus, and A. oryzae. The spent medium of A. niger showed the highest silver reduction capacities with up to 15 μmol per milliliter spent medium when ammonium was used as the sole N-source. Silver ion reduction in the spent medium was not driven by enzymes and did not correlate with biomass concentration. Nearly full reduction capacity was reached after 2 days of incubation, long before the cessation of growth and onset of the stationary phase. The size of silver nanoparticles formed in the spent medium of A. niger was influenced by the nitrogen source, with silver nanoparticles formed in nitrate or ammonium-containing medium having an average diameter of 32 and 6 nm, respectively. 相似文献
12.
Peter JC Nicholson JR Heydet D Lecourt AC Hoebeke J Hofbauer KG 《American journal of physiology. Regulatory, integrative and comparative physiology》2007,292(6):R2151-R2158
Functionally active antibodies (Abs) against central G-protein-coupled receptors have not yet been reported. We selected the hypothalamic melanocortin-4 receptor (MC4-R) as a target because of its crucial role in the regulation of energy homeostasis. A 15 amino acid sequence of the N-terminal (NT) domain was used as an antigen. This peptide showed functional activity in surface plasmon resonance experiments and in studies on HEK-293 cells overexpressing the human MC4-R (hMC4-R). Rats immunized against the NT peptide produced specific antibodies, which were purified and characterized in vitro. In HEK-293 cells, rat anti-NT Abs showed specific immunofluorescence labeling of hMC4-R. They reduced the production of cAMP under basal conditions and after stimulation with a synthetic MC4-R agonist. Rats immunized against the NT peptide developed a phenotype consistent with MC4-R blockade, that is, increased food intake and body weight, increased liver and fat pad weight, and elevated plasma triglycerides. In a separate experiment in rats, an increase in food intake could be produced after injection of purified Abs into the third ventricle. Similar results were obtained in rats injected with anti-NT Abs raised in rabbits. Our data show for the first time that active immunization of rats against the NT sequence of the MC4-R results in specific Abs, which appear to stimulate food intake by acting as inverse agonists in the hypothalamus. 相似文献
13.
14.
Novel aspects of osteoclast activation and osteoblast inhibition in myeloma bone disease 总被引:3,自引:0,他引:3
Heider U Hofbauer LC Zavrski I Kaiser M Jakob C Sezer O 《Biochemical and biophysical research communications》2005,338(2):687-693
Increased bone resorption is a major characteristic of multiple myeloma and is caused by osteoclast activation and osteoblast inhibition (uncoupling). Myeloma cells alter the local regulation of bone metabolism by increasing the receptor activator of NF-kappaB ligand (RANKL) and decreasing osteoprotegerin expression within the bone marrow microenvironment, thereby stimulating the central pathway for osteoclast formation and activation. In addition, they produce the chemokines MIP-1alpha, MIP-1beta, and SDF-1alpha, which also increase osteoclast activity. On the other hand, myeloma cells suppress osteoblast function by the secretion of osteoblast inhibiting factors, e.g., the Wnt inhibitors DKK-1 and sFRP-2. Moreover, they inhibit differentiation of osteoblast precursors and induce apoptosis in osteoblasts. The resulting bone destruction releases several cytokines, which in turn promote myeloma cell growth. Therefore, the inhibition of bone resorption could stop this vicious circle and not only decrease myeloma bone disease, but also the tumor progression. 相似文献
15.
In the present studies, we used a non-selective melanocortin MC3/4 receptor agonist (HP228) and a novel selective melanocortin MC4 receptor (MC4-R) agonist (MK-cpd1) to study the cardiovascular, temperature, locomotor and feeding responses to melanocortin receptor stimulation in comparison to sibutramine in rats instrumented with a telemetry transmitter. Moreover, norepinephrine turnover rates in heart and brown adipose tissue were determined. HP228 (1, 3 and 10mg/kg, i.p.) reduced 24h food intake dose-dependently and increased heart rate and mean arterial pressure (maximal differences: +60+/-8beats/min and +8+/-1mmHg, means+/-S.E.M., p<0.001 and p<0.01, respectively). After 10mg/kg HP228 showed a three-fold increase in norepinephrine turnover in the heart. The selective MC4-R agonist MK-cpd1 tended to decrease 24h food intake only at the highest dose tested (10mg/kg, i.p., p=0.06) and increased both heart rate (+17+/-4 and +22+/-5beats/min at 3 and 10mg/kg, p<0.01) and mean arterial pressure (+4+/-1mmHg at 10mg/kg, p<0.05). Sibutramine reduced food intake at all doses tested (1, 3 and 10mg/kg, i.p.). It did not change mean arterial pressure significantly, and increased heart rate only at the highest dose tested (+36+/-6beats/min, p<0.05). If also observed in humans, the pharmacological profile of MC4-R agonists would not offer a significant therapeutic advantage over currently used appetite suppressants such as sibutramine. 相似文献
16.
Gross-Langenhoff M Hofbauer K Weber J Schultz A Schultz JE 《The Journal of biological chemistry》2006,281(5):2841-2846
N-terminal tandem GAF domains are present in 5 out of 11 mammalian phosphodiesterase (PDE) families. The ligand for the GAF domains of PDEs 2, 5, and 6 is cGMP, whereas those for PDEs 10 and 11 remained enigmatic for years. Here we used the cyanobacterial cyaB1 adenylyl cyclase, which has an N-terminal tandem GAF domain closely related to those of the mammalian PDEs, as an assay system to identify the ligands for the human PDEs 10 and 11 GAF domains. We report that a chimera between the PDE10 GAF domain and the cyanobacterial cyclase was 9-fold stimulated by cAMP (EC50= 19.8 microm), whereas cGMP had only low activity. cAMP increased Vmax in a non-cooperative manner and did not affect the Km for ATP of 27 microm. In an analogous chimeric construct with the tandem GAF domain of human PDE11A4, cGMP was identified as an allosteric activator (EC50 = 72.5 microm) that increased Vmax of the cyclase non-cooperatively 4-fold. GAF-B of PDE10 and GAF-A of PDE11A4 contain an invariant NKFDE motif present in all mammalian PDE GAF ensembles. We mutated the aspartates within this motif in both regions and found that intramolecular signaling was considerably reduced or abolished. This was in line with all data concerning GAF domains with an NKFDE motif as far as they have been tested. The data appeared to define those GAF domains as a distinct subclass within the >3100 annotated GAF domains for which we propose a tentative classification scheme. 相似文献
17.
Amrhein I Wurth C Bohner T Hofbauer R Folkers G Scapozza L 《Protein expression and purification》2000,18(3):338-345
Recombinant varicella zoster virus (VZV) thymidine kinase (TK) was isolated in a fast and gentle two-step procedure from Escherichia coli. The TK was expressed as a PreScission-cleavable fusion protein and purified by glutathione and ATP affinity chromatography, yielding homogeneous, highly pure VZV TK. The purified enzyme displays enzymatic activities with K(m) values of 0.3 +/- 0.06 microM for the natural substrate thymidine and 11.6 +/- 3.2 microM for ATP, indicating the biochemical equivalence with the viral VZV TK expressed in infected cells. Determinations of the native molecular weight by size exclusion chromatography and native polyacrylamide gel electrophoresis revealed that the pure enzyme is biologically active as a homodimer. 相似文献
18.
Hofbauer S Gysel K Mlynek G Kostan J Hagmüller A Daims H Furtmüller PG Djinović-Carugo K Obinger C 《Biochimica et biophysica acta》2012,1824(9):1031-1038
Chlorite dismutases (Cld) are unique heme b containing oxidoreductases that convert chlorite to chloride and dioxygen. Recent phylogenetic and structural analyses demonstrated that these metalloproteins significantly differ in oligomeric and subunit structure. Here we have analyzed two representatives of two phylogenetically separated lineages, namely pentameric Cld from Candidatus "Nitrospira defluvii" and dimeric Cld from Nitrobacter winogradskyi having a similar enzymatic activity at room temperature. By application of a broad set of techniques including differential scanning calorimetry, electronic circular dichroism, UV-vis and fluorescence spectroscopy the temperature-mediated and chemical unfolding of both recombinant proteins were analyzed. Significant differences in thermal and conformational stability are reported. The pentameric enzyme is very stable between pH 3 and 10 (T(m)=92°C at pH 7.0) and active at high temperatures thus being an interesting candidate for bioremediation of chlorite. By contrast the dimeric protein starts to unfold already at 53°C. The observed unfolding pathways are discussed with respect to the known subunit structure and subunit interaction. 相似文献
19.
20.
In signaling games the replicator dynamics does not almost always converge to states of perfect communication. A significant portion of the state space converges to components of Nash equilibria that characterize states of partial communication. Since these components consist of non-hyperbolic rest points, the significance of this result will depend on the dynamic behavior of specific perturbations of the replicator equations. In this paper we study selection-mutation dynamics of signaling games, which may be considered as one plausible perturbation of the replicator dynamics. We find that the long term behavior of the dynamics depends on the mutation rates of senders and receivers and on the relevance of communication. 相似文献