14,538 research outputs found
Insights into the molecular basis for substrate binding and specificity of the wild-type L-arginine/agmatine antiporter AdiC.
No full textPathogenic enterobacteria need to survive the extreme acidity of the stomach to successfully colonize the human gut. Enteric bacteria circumvent the gastric acid barrier by activating extreme acid-resistance responses, such as the arginine-dependent acid resistance system. In this response, l-arginine is decarboxylated to agmatine, thereby consuming one proton from the cytoplasm. In Escherichia coli, the l-arginine/agmatine antiporter AdiC facilitates the export of agmatine in exchange of l-arginine, thus providing substrates for further removal of protons from the cytoplasm and balancing the intracellular pH. We have solved the crystal structures of wild-type AdiC in the presence and absence of the substrate agmatine at 2.6-Å and 2.2-Å resolution, respectively. The high-resolution structures made possible the identification of crucial water molecules in the substrate-binding sites, unveiling their functional roles for agmatine release and structure stabilization, which was further corroborated by molecular dynamics simulations. Structural analysis combined with site-directed mutagenesis and the scintillation proximity radioligand binding assay improved our understanding of substrate binding and specificity of the wild-type l-arginine/agmatine antiporter AdiC. Finally, we present a potential mechanism for conformational changes of the AdiC transport cycle involved in the release of agmatine into the periplasmic space of E. coli
Joannes de boetgezant : begrepen in zes boecken /
No full textVingerafdruk: 169604 - b1 A2 $hee : *b2 Q leA2, l. 5-6: verkoren, | voorDrukkersmerk.Another issue of the other edition Amsterdam, wed. G. de Groot, 1696.Europeana-GoogleBook
Een woonomgeving voor het leven: Middels de transformatie van een voormalige serviceflat in Groot-IJsselmonde
No full textHet ontwerp is een transformatievoorstel voor 'Woongebouw De Kreek' in Groot-IJsselmonde in Rotterdam. Waar het onderzoek vooral op de woonbehoeftes van (kwetsbare) ouderen is gericht, is het ontwerp een woonomgeving voor verschillende doelgroepen.VeldacademieArchitectureArchitecture and The Built Environmen
Self-aligned silicidation of surround gate vertical MOSFETs for low cost RF applications
No full textWe report for the first time a CMOS-compatible silicidation technology for surround-gate vertical MOSFETs. The technology uses a double spacer comprising a polysilicon spacer for the surround gate and a nitride spacer for silicidation and is successfully integrated with a Fillet Local OXidation (FILOX) process, which thereby delivers low overlap capacitance and high drive-current vertical devices. Silicided 80-nm vertical n-channel devices fabricated using 0.5-?m lithography are compared with nonsilicided devices. A source–drain (S/D) activation anneal of 30 s at 1100 ?C is shown to deliver a channel length of 80 nm, and the silicidation gives a 60% improvement in drive current in comparison with nonsilicided devices. The silicided devices exhibit a subthreshold slope (S) of 87 mV/dec and a drain-induced barrier lowering (DIBL) of 80 mV/V, compared with 86 mV/dec and 60 mV/V for nonsilicided devices. S-parameter measurements on the 80-nm vertical nMOS devices give an fT of 20 GHz, which is approximately two times higher than expected for comparable lateral MOSFETs fabricated using the same 0.5-?m lithography. Issues associated with silicidation down the pillar sidewall are investigated by reducing the activation anneal time to bring the silicided region closer to the p-n junction at the top of the pillar. In this situation, nonlinear transistor turn-on is observed in drain-on-top operation and dramatically degraded drive current in source-on-top operation. This behavior is interpreted using mixed-mode simulations, which show that a Schottky contact is formed around the perimeter of the pillar when the silicided contact penetrates too close to the top S/D junction down the side of the pillar
Getting evidence into nursing practice: roles of social context
No full textContains fulltext :
129659.pdf (Publisher’s version ) (Open Access)Radboud Universiteit Nijmegen, 15 september 2014Promotor : Achterberg, T. van Co-promotores : Schoonhoven, L., Mintjes-de Groot, A.J
Critically ill, well assessed. Evaluation of the rapid response system in a university medical center
No full textContains fulltext :
129681.pdf (Publisher’s version ) (Open Access)Radboud Universiteit Nijmegen, 26 september 2014Promotor : Hoeven, J.G. van der Co-promotores : Schoonhoven, L., Mintjes-de Groot, A.J
Dataset for Back-end-of-line a-SiOxCy:H dielectrics for resistive memory
No full textDataset of figures in the paper Fan, J., Kapur, O., Huang, R., De Groot, C., & Jiang, L. (2018). Back-end-of-line a-SiOxCy:H dielectrics for resistive memory. AIP Advances. This dataset including XPS on a-SiOxCy:H films and current-voltage measurements tests on W/a-SiOxCy:H/Cu resistive memories.</span
Determinants of water permeability through nanoscopic hydrophilic channels.
No full textAbstractNaturally occurring pores show a variety of polarities and sizes that are presumably directly linked to their biological function. Many biological channels are selective toward permeants similar or smaller in size than water molecules, and therefore their pores operate in the regime of single-file water pores. Intrinsic factors affecting water permeability through such pores include the channel-membrane match, the structural stability of the channel, the channel geometry and channel-water affinity. We present an extensive molecular dynamics study on the role of the channel geometry and polarity on the water osmotic and diffusive permeability coefficients. We show that the polarity of the naturally occurring peptidic channels is close to optimal for water permeation, and that the water mobility for a wide range of channel polarities is essentially length independent. By systematically varying the geometry and polarity of model hydrophilic pores, based on the fold of gramicidin A, the water density, occupancy, and permeability are studied. Our focus is on the characterization of the transition between different permeation regimes in terms of the structure of water in the pores, the average pore occupancy and the dynamics of the permeating water molecules. We show that a general relationship between osmotic and diffusive water permeability coefficients in the single-file regime accounts for the time averaged pore occupancy, and that the dynamics of the permeating water molecules through narrow non single file channels effectively behaves like independent single-file columns
Protein thermostability calculations using alchemical free energy simulations.
No full textAbstractThermal stability of proteins is crucial for both biotechnological and therapeutic applications. Rational protein engineering therefore frequently aims at increasing thermal stability by introducing stabilizing mutations. The accurate prediction of the thermodynamic consequences caused by mutations, however, is highly challenging as thermal stability changes are caused by alterations in the free energy of folding. Growing computational power, however, increasingly allows us to use alchemical free energy simulations, such as free energy perturbation or thermodynamic integration, to calculate free energy differences with relatively high accuracy. In this article, we present an automated protocol for setting up alchemical free energy calculations for mutations of naturally occurring amino acids (except for proline) that allows an unprecedented, automated screening of large mutant libraries. To validate the developed protocol, we calculated thermodynamic stability differences for 109 mutations in the microbial Ribonuclease Barnase. The obtained quantitative agreement with experimental data illustrates the potential of the approach in protein engineering and design
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