Catálogo de publicaciones - revistas

<jats:title>Energy conversion in complex 1</jats:title> <jats:p> ATP, the energy source of the cell, is synthesized by a protein residing in the mitochondrial inner membrane. The synthesis is driven by a proton gradient generated by redox reactions that transfer electrons between a series of enzymes in the membrane. The largest complex in this electron transfer chain is the 1-MD complex 1. It couples electron transfer from NADH to ubiquinone to the translocation of four protons. Zickermann <jats:italic>et al.</jats:italic> report the crystal structure of a complex comprising the 14 central subunits and the largest accessory subunit of mitochondrial complex 1 from a yeast-genetic model at 3.6 Ã… resolution. The structure identifies four potential proton translocation pathways and gives insight into how energy from the redox reactions is transmitted to drive proton pumping. </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="6217" page="44" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.1259859">44</jats:related-article> </jats:p>

<jats:title>Breaking through the milligram floor</jats:title> <jats:p> When chemists synthesize compounds, the threshold for success is at least a milligram of product. This has been true for decades—even though biochemical assays have long since descended into microgram territory—and results in part from the constraints of characterization methods. Buitrago Santanilla <jats:italic>et al.</jats:italic> present an automated dosing and characterization protocol for optimizing chemical reaction conditions on the microgram scale. This allowed them to screen numerous base and ligand combinations for catalytic C-N bond-forming reactions between complex pairs of compounds, in short supply, that resisted standard coupling conditions. </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="6217" page="49" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.1259203">49</jats:related-article> </jats:p>

<jats:title>Engineering a shelter for quantum protection</jats:title> <jats:p> In isolation, quantum states of matter can be stable entities. These states are often seen as useful when they can be made to interact in a controlled way. However, those interactions and the unavoidable interactions with their environment often correlate with decoherence and eventual loss of the quantum state. Kienzler <jats:italic>et al.</jats:italic> show that they can engineer the interactions between a quantum system (a trapped ion) and the environment to prepare stable quantum states. The generality of the technique implies applications for other interacting quantum systems. </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="6217" page="53" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.1261033">53</jats:related-article> </jats:p>

<jats:title>Shifting hydroformylation into reverse</jats:title> <jats:p> The hydroformylation reaction is applied on large scale in the chemical industry to make aldehydes by adding hydrogen and carbon monoxide to olefins. The reverse process could also prove useful in modifying complex molecules for pharmaceutical research, but methods directed toward that end often strip off the CO without the hydrogen. Murphy <jats:italic>et al.</jats:italic> now show that a rhodium catalyst can achieve selective dehydroformylation of a diverse range of compounds under mild conditions (see the Perspective by Landis). The protocol relies on effective transfer of the CO and H <jats:sub>2</jats:sub> equivalents to a sacrificial strained olefin added to the mix. </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="6217" page="56" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.1261232">56</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6217" page="29" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.aaa2329">29</jats:related-article> </jats:p>

<jats:title>A few very brief pauses in the action</jats:title> <jats:p> Chemical reactions proceed by the cumulative effect of trillions upon trillions of collisions between atoms and molecules. Usually, a given collision bounces the participants right back out again, either in their original form or with the atoms shuffled around into distinct products. In certain cases, the reacting partners experience a brief lull, termed a resonance, before they rearrange. Yang <jats:italic>et al.</jats:italic> report the discovery of particularly short-lived resonances in certain reactive collisions of chlorine atoms with vibrationally excited hydrogen deuteride (HD). Their results suggest that similar, as yet overlooked, resonances may lurk in other reactions of vibrationally excited molecules. </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="6217" page="60" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.1260527">60</jats:related-article> </jats:p>

<jats:title>Killing, sex, and gene swaps in bacteria</jats:title> <jats:p> The bacterial type VI secretion system (T6SS) is used by bacteria to inject toxins into neighboring cells to eliminate competition. This molecular machine is thus considered to be a mechanism by which bacteria can exert social control in complex microbial communities. Borgeaud <jats:italic>et al.</jats:italic> have discovered that in <jats:italic>Vibrio cholerae</jats:italic> , T6SS genes are co-regulated with genes involved in DNA uptake. Hence, T6SS-dependent killing of other bacteria is directed at neighboring cells, which release their DNA to be taken up by the killer, which can then integrate valuable genes and rapidly evolve, leading to antibiotic resistance or virulence. </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="6217" page="63" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.1260064">63</jats:related-article> </jats:p>