Catálogo de publicaciones - revistas

<jats:title>How calcium gates a potassium channel</jats:title> <jats:p> Small-conductance Ca <jats:sup>2+</jats:sup> -activated K <jats:sup>+</jats:sup> (SK) channels are expressed throughout the nervous system and affect both the intrinsic excitability of neurons and synaptic transmission. An increase in the concentration of intracellular calcium opens the channels to conduct potassium across the cell membrane. Lee and MacKinnon report cryo–electron microscopy structures of human SK4-calmodulin channel complexes. Activation occurs when calcium binds to calmodulin, a protein with two lobes, known as C and N, separated by a flexible region. Each monomer in the channel tetramer binds constitutively to the C-lobe of calmodulin. The N-lobe of calmodulin is reasonably unconstrained until it binds calcium. With calcium bound, it then binds to the channel and induces conformational changes that open the pore. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6388" page="508" related-article-type="in-this-issue" vol="360" xlink:href="10.1126/science.aas9466">508</jats:related-article> </jats:p>

<jats:title>Retrosynthesizing complex nanostructures</jats:title> <jats:p> The solution synthesis of complex and asymmetric nanostructures is still challenging. For many applications, it will be important to gain simultaneous control over particle size and morphology, constituent materials, and internal interfaces. Fenton <jats:italic>et al.</jats:italic> have developed a strategy that mimics chemical retrosynthesis, starting with simple nanoparticle synthons—in this case, Cu <jats:sub>1.8</jats:sub> S nanoparticles, nanorods, and nanosheets. Various types of interfaces and junctions can be introduced, for example, by cation substitution. This intervention breaks the symmetry of the synthons and assembles them into higher-order structures. The nanostructures can thus be formed with asymmetric, patchy, porous, or sculpted regions. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6388" page="513" related-article-type="in-this-issue" vol="360" xlink:href="10.1126/science.aar5597">513</jats:related-article> </jats:p>

<jats:title>Turing structures at the nanoscale</jats:title> <jats:p> Turing structures arise when imbalances in diffusion rates make a stable steady-state system sensitive to small heterogeneous perturbations. For example, Turing patterns occur in chemical reactions when a fast-moving inhibitor controls the motion of a slower-moving activator. Tan <jats:italic>et al.</jats:italic> grew polyamide membranes by using interfacial polymerization, where the reactions occur at the interface between oil and water layers. The addition of polyvinyl alcohol to the aqueous phase reduced the diffusion of the monomer. This process generates membranes with more bumps, voids, and islands, which prove to be better for water desalination. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6388" page="518" related-article-type="in-this-issue" vol="360" xlink:href="10.1126/science.aar6308">518</jats:related-article> </jats:p>

<jats:title>Direct plasmon chemistry</jats:title> <jats:p> Light can excite plasmons at a metal surface, which can then decay and create hot electrons that induce chemical reactions of adsorbed molecules. Kazuma <jats:italic>et al.</jats:italic> used a scanning tunneling microscope (STM) to induce and map out the surface dissociation of a dimethyl disulfide molecule on silver and copper surfaces. A silver STM tip created localized plasmons at different distances from the molecule. The plasmons drove the reaction directly by exciting the valence electrons of the molecule into unoccupied states and cleaving the sulfur-sulfur bond. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6388" page="521" related-article-type="in-this-issue" vol="360" xlink:href="10.1126/science.aao0872">521</jats:related-article> </jats:p>