Mechanism for Variable Selectivity and Conductance in Mutated NaK Channels

Na⁺ conduction has been demonstrated in a few K⁺ channels and has been widely used to characterize the physiological selectivity and C-type inactivation in K⁺ channels. By using molecular dynamics simulations and free-energy calculations, we found that K⁺ and Na⁺ have distinct preferable binding configurations in the conductive filter of two highly K⁺ selective channels, which are mutated from the nonselective NaK channel and can conduct Na⁺ upon removal of K⁺. Disruption of a conserved hydrogen bond interaction between residues in the filter and the pore helices can significantly decrease the free-energy differences and barriers between the K⁺ binding configurations, whereas it has little effect on the free-energy landscape for Na⁺. We propose that the enhancement of the fluctuation of the filter structure decreases the affinity and conducting barrier of K⁺ and therefore the ability of K⁺ to block Na⁺ currents, predominantly responsible for the reduced K⁺ selectivity

Self-Adjusted Sustaining Oscillation of Confined Water Chain in Carbon Nanotubes

We show by molecular dynamics and first principle calculations that a water chain confined in carbon nanotubes can self-adjust into regular oscillation with remarkably lower entropy from random thermal motion with higher entropy at room temperature. The turning between the two phases is triggered by the water orientation fluttering into or from the energy optimum configuration of the chain. The findings are expected to be helpful in creation of self-sustaining nanoelectromechanical systems driven by ambient energy

Data for: The cardiovascular toxicity induced by gatifloxacin and ciprofloxacin in zebrafish

the data for the cardiovascular toxicity induced by gatifloxacin and ciprofloxacin in zebrafis

Exciton–Phonon Coupling and Low Energy Emission in 2D and Quasi-2D BA₂MA_<i>n</i>–1Pb_<i>n</i>I_3<i>n</i>+1 Thin Films with Improved Phase Purity

Phonon scattering with photogenerated excitons and free charges greatly affects optoelectronic properties of metal halide perovskites and governs their emission line width. Benefiting from the improved phase purity, we are able to analyze exciton–phonon coupling in 2D and quasi-2D BA2MAn–1PbnI3n+1 (n = 1–3) thin films using temperature-dependent photoluminescence (PL) spectroscopy. The layer thickness (n value) dependent coupling of free excitons with both acoustic and longitudinal optical (LO) phonons was extracted quantitatively by fitting the temperature-dependent PL line width and band gap. The low energy emissive signatures below free excitons at low temperature might belong to the emission of self-trapped excitons and bounded excitons in structural defects. Our findings provide a systematic picture for the layer thickness (n value) dependent exciton–phonon coupling in 2D and quasi-2D perovskite thin films and could be helpful for improving the optoelectronic performance of devices made by Ruddlesden–Popper perovskite thin films

Exciton–Phonon Coupling and Low Energy Emission in 2D and Quasi-2D BA₂MA_<i>n</i>–1Pb_<i>n</i>I_3<i>n</i>+1 Thin Films with Improved Phase Purity

Phonon scattering with photogenerated excitons and free charges greatly affects optoelectronic properties of metal halide perovskites and governs their emission line width. Benefiting from the improved phase purity, we are able to analyze exciton–phonon coupling in 2D and quasi-2D BA2MAn–1PbnI3n+1 (n = 1–3) thin films using temperature-dependent photoluminescence (PL) spectroscopy. The layer thickness (n value) dependent coupling of free excitons with both acoustic and longitudinal optical (LO) phonons was extracted quantitatively by fitting the temperature-dependent PL line width and band gap. The low energy emissive signatures below free excitons at low temperature might belong to the emission of self-trapped excitons and bounded excitons in structural defects. Our findings provide a systematic picture for the layer thickness (n value) dependent exciton–phonon coupling in 2D and quasi-2D perovskite thin films and could be helpful for improving the optoelectronic performance of devices made by Ruddlesden–Popper perovskite thin films

Regulation pathways involving mitochondrial proteins in pre-eclamptic placentae as predicted by PathwayStudio^TM software.

<p>Proteins are shown as red ovals, regulated processes are represented by yellow squares. Regulation events are displayed with arrows and documented by literature citations.</p

Characteristics and outcomes of control and SPE cases.

<p>Data are presented as mean ± SEM.</p><p>C: Control, P: Patient.</p

Immunohistochemical staining for HSPE1, PRDX3 and TFRC in the placental tissue of SPE patients and controls.

<p>The staining for HSPE1, PRDX3 and TFRC in the cytoplasm of syncytiotrophoblastic and/or cytotrophoblastic cells was more intense in the placental tissue from SPE patients compared with the controls.</p

Full list of the 26 proteins identified by iTRAQ labeling-based proteomics.

<p>The key proteins verified by Western blot analysis are highlighted in bold. The corresponding average ratios between the two groups (control/SPE) are given.</p

Structural Refinement of Proteins by Restrained Molecular Dynamics Simulations with Non-interacting Molecular Fragments

<div><p>The knowledge of multiple conformational states is a prerequisite to understand the function of membrane transport proteins. Unfortunately, the determination of detailed atomic structures for all these functionally important conformational states with conventional high-resolution approaches is often difficult and unsuccessful. In some cases, biophysical and biochemical approaches can provide important complementary structural information that can be exploited with the help of advanced computational methods to derive structural models of specific conformational states. In particular, functional and spectroscopic measurements in combination with site-directed mutations constitute one important source of information to obtain these mixed-resolution structural models. A very common problem with this strategy, however, is the difficulty to simultaneously integrate all the information from multiple independent experiments involving different mutations or chemical labels to derive a unique structural model consistent with the data. To resolve this issue, a novel restrained molecular dynamics structural refinement method is developed to simultaneously incorporate multiple experimentally determined constraints (e.g., engineered metal bridges or spin-labels), each treated as an individual molecular fragment with all atomic details. The internal structure of each of the molecular fragments is treated realistically, while there is no interaction between different molecular fragments to avoid unphysical steric clashes. The information from all the molecular fragments is exploited simultaneously to constrain the backbone to refine a three-dimensional model of the conformational state of the protein. The method is illustrated by refining the structure of the voltage-sensing domain (VSD) of the Kv1.2 potassium channel in the resting state and by exploring the distance histograms between spin-labels attached to T4 lysozyme. The resulting VSD structures are in good agreement with the consensus model of the resting state VSD and the spin-spin distance histograms from ESR/DEER experiments on T4 lysozyme are accurately reproduced.</p></div