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ACS Central Science

Shentian Zhuang, Qiang Li, Lirong Cai, Chu Wang, Xiaoguang Lei
Bile acids (BAs) are a family of endogenous metabolites synthesized from cholesterol in liver and modified by microbiota in gut. Being amphipathic molecules, the major function of BAs is to help with dietary lipid digestion. In addition, they also act as signaling molecules to regulate lipid and glucose metabolism as well as gut microbiota composition in the host. Remarkably, recent discoveries of the dedicated receptors for BAs such as FXR and TGR5 have uncovered a number of novel actions of BAs as signaling hormones which play significant roles in both physiological and pathological conditions...
May 24, 2017: ACS Central Science
Paul J O'Brien, Sina Elahipanah, Dmitry Rogozhnikov, Muhammad N Yousaf
The efficient delivery of foreign nucleic acids (transfection) into cells is a critical tool for fundamental biomedical research and a pillar of several biotechnology industries. There are currently three main strategies for transfection including reagent, instrument, and viral based methods. Each technology has significantly advanced cell transfection; however, reagent based methods have captured the majority of the transfection market due to their relatively low cost and ease of use. This general method relies on the efficient packaging of a reagent with nucleic acids to form a stable complex that is subsequently associated and delivered to cells via nonspecific electrostatic targeting...
May 24, 2017: ACS Central Science
Jie Zhao, Son C Nguyen, Rong Ye, Baihua Ye, Horst Weller, Gábor A Somorjai, A Paul Alivisatos, F Dean Toste
Light driven excitation of gold nanoparticles (GNPs) has emerged as a potential strategy to generate hot carriers for photocatalysis through excitation of localized surface plasmon resonance (LSPR). In contrast, carrier generation through excitation of interband transitions remains a less explored and underestimated pathway for photocatalytic activity. Photoinduced oxidative etching of GNPs with FeCl3 was investigated as a model reaction in order to elucidate the effects of both types of transitions. The quantitative results show that interband transitions more efficiently generate hot carriers and that those carriers exhibit higher reactivity as compared to those generated solely by LSPR...
May 24, 2017: ACS Central Science
Dong Liu, Wen-Hao Wu, Ya-Jie Liu, Xia-Ling Wu, Yang Cao, Bo Song, Xiaopeng Li, Wen-Bin Zhang
Recombinant proteins are traditionally limited to linear configuration. Herein, we report in vivo protein topology engineering using highly efficient, mechanically interlocking SpyX modules named AXB and BXA. SpyX modules are protein domains composed of p53dim (X), SpyTag (A), and SpyCatcher (B). The p53dim guides the intertwining of the two nascent protein chains followed by autocatalytic isopeptide bond formation between SpyTag and SpyCatcher to fulfill the interlocking, leading to a variety of backbone topologies...
May 24, 2017: ACS Central Science
Minoru Ueda, Syusuke Egoshi, Kosuke Dodo, Yasuhiro Ishimaru, Hiroyuki Yamakoshi, Takeshi Nakano, Yousuke Takaoka, Shinya Tsukiji, Mikiko Sodeoka
Coronatine (1), a small-molecular virulence factor produced by plant-pathogenic bacteria, promotes bacterial infection by inducing the opening of stomatal pores, the major route of bacterial entry into the plant, via the jasmonate-mediated COI1-JAZ signaling pathway. However, this pathway is also important for multiple plant functions, including defense against wounding by herbivorous insects. Thus, suppression of the COI1-JAZ signaling pathway to block bacterial infection would concomitantly impair plant defense against herbivorous wounding...
May 24, 2017: ACS Central Science
Massimiliano Porrini, Frédéric Rosu, Clémence Rabin, Leonardo Darré, Hansel Gómez, Modesto Orozco, Valérie Gabelica
We report on the fate of nucleic acids conformation in the gas phase as sampled using native mass spectrometry coupled to ion mobility spectrometry. On the basis of several successful reports for proteins and their complexes, the technique has become popular in structural biology, and the conformation survival becomes more and more taken for granted. Surprisingly, we found that DNA and RNA duplexes, at the electrospray charge states naturally obtained from native solution conditions (≥100 mM aqueous NH4OAc), are significantly more compact in the gas phase compared to the canonical solution structures...
May 24, 2017: ACS Central Science
Lili Zong, Eline Bartolami, Daniel Abegg, Alexander Adibekian, Naomi Sakai, Stefan Matile
The disulfide dihedral angle in epidithiodiketopiperazines (ETPs) is near 0°. Application of this highest possible ring tension to strain-promoted thiol-mediated uptake results in efficient delivery to the cytosol and nucleus. Compared to the previous best asparagusic acid (AspA), ring-opening disulfide exchange with ETPs occurs more efficiently even with nonactivated thiols, and the resulting thiols exchange rapidly with nonactivated disulfides. ETP-mediated cellular uptake is more than 20 times more efficient compared to AspA, occurs without endosomal capture, depends on temperature, and is "unstoppable" by inhibitors of endocytosis and conventional thiol-mediated uptake, including siRNA against the transferrin receptor...
May 24, 2017: ACS Central Science
Hoyoung D Park, Mircea Dincă, Yuriy Román-Leshkov
Despite the commercial desirability of epoxide carbonylation to β-lactones, the reliance of this process on homogeneous catalysts makes its industrial application challenging. Here we report the preparation and use of a Co(CO)4(-)-incorporated Cr-MIL-101 (Co(CO)4⊂Cr-MIL-101, Cr-MIL-101 = Cr3O(BDC)3F, H2BDC = 1,4-benzenedicarboxylic acid) heterogeneous catalyst for the ring-expansion carbonylation of epoxides, whose activity, selectivity, and substrate scope are on par with those of the reported homogeneous catalysts...
May 24, 2017: ACS Central Science
Connor W Coley, Regina Barzilay, Tommi S Jaakkola, William H Green, Klavs F Jensen
Computer assistance in synthesis design has existed for over 40 years, yet retrosynthesis planning software has struggled to achieve widespread adoption. One critical challenge in developing high-quality pathway suggestions is that proposed reaction steps often fail when attempted in the laboratory, despite initially seeming viable. The true measure of success for any synthesis program is whether the predicted outcome matches what is observed experimentally. We report a model framework for anticipating reaction outcomes that combines the traditional use of reaction templates with the flexibility in pattern recognition afforded by neural networks...
May 24, 2017: ACS Central Science
Kelly S Burke, Katie A Antilla, David A Tirrell
Single-molecule fluorescence in situ hybridization (smFISH) is a simple and widely used method to measure mRNA transcript abundance and localization in single cells. A comparable single-molecule in situ method to measure mRNA translation would enable a more complete understanding of gene regulation. Here we describe a fluorescence assay to detect ribosome interactions with mRNA (FLARIM). The method adapts smFISH to visualize and characterize translation of single molecules of mRNA in fixed cells. To visualize ribosome-mRNA interactions, we use pairs of oligonucleotide probes that bind separately to ribosomes (via rRNA) and to the mRNA of interest, and that produce strong fluorescence signals via the hybridization chain reaction (HCR) when the probes are in close proximity...
May 24, 2017: ACS Central Science
Lucas W Antony, Nicholas E Jackson, Ivan Lyubimov, Venkatram Vishwanath, Mark D Ediger, Juan J de Pablo
Organic glass films formed by physical vapor deposition exhibit enhanced stability relative to those formed by conventional liquid cooling and aging techniques. Recently, experimental and computational evidence has emerged indicating that the average molecular orientation can be tuned by controlling the substrate temperature at which these "stable glasses" are grown. In this work, we present a comprehensive all-atom simulation study of ethylbenzene, a canonical stable-glass former, using a computational film formation procedure that closely mimics the vapor deposition process...
May 24, 2017: ACS Central Science
Jun Zhang, Zhen Zhang, Yi Isaac Yang, Sirui Liu, Lijiang Yang, Yi Qin Gao
Efficient sampling in both configuration and trajectory spaces, combined with mechanism analyses via data mining, allows a systematic investigation of the thermodynamics, kinetics, and molecular-detailed dynamics of chemical reactions in solution. Through a Bayesian learning algorithm, the reaction coordinate(s) of a (retro-)Claisen rearrangement in bulk water was variationally optimized. The bond formation/breakage was found to couple with intramolecular charge separation and dipole change, and significant dynamic solvent effects manifest, leading to the "in-water" acceleration of Claisen rearrangement...
May 24, 2017: ACS Central Science
Ashleigh L Ward, Sean E Doris, Longjun Li, Mark A Hughes, Xiaohui Qu, Kristin A Persson, Brett A Helms
Selective ion transport across membranes is critical to the performance of many electrochemical energy storage devices. While design strategies enabling ion-selective transport are well-established, enhancements in membrane selectivity are made at the expense of ionic conductivity. To design membranes with both high selectivity and high ionic conductivity, there are cues to follow from biological systems, where regulated transport of ions across membranes is achieved by transmembrane proteins. The transport functions of these proteins are sensitive to their environment: physical or chemical perturbations to that environment are met with an adaptive response...
May 24, 2017: ACS Central Science
Aziz Ghoufi, Karima Benhamed, Leila Boukli-Hacene, Guillaume Maurin
The breathing behavior of the MIL-53(Cr) metal-organic framework (MOF) has been explored previously upon guest-adsorption and thermal and mechanical stimuli. Here, advanced molecular simulations based on the use of an accurate force field to describe the flexibility of this porous framework demonstrate that the application of an electrical field induces the structural switching of this MOF leading to a first-order transition and a volume change of more than 40%. This motivated us to electrically tune the pore size of MIL-53(Cr) with the idea to propose a new concept to selectively capture CO2 over CH4 via a molecular sieving that paves the way toward the optimization of current separation-based processes...
May 24, 2017: ACS Central Science
Douglas Zhang, Junmin Lee, Michael B Sun, Yi Pei, James Chu, Martha U Gillette, Timothy M Fan, Kristopher A Kilian
The tumor microenvironment is implicated in orchestrating cancer cell transformation and metastasis. However, specific cell-ligand interactions between cancer cells and the extracellular matrix are difficult to decipher due to a dynamic and multivariate presentation of many signaling molecules. Here we report a versatile peptide microarray platform that is capable of screening for cancer cell phenotypic changes in response to ligand-receptor interactions. Using a screen of 78 peptide combinations derived from proteins present in the melanoma microenvironment, we identify a proteoglycan binding and bone morphogenic protein 7 (BMP7) derived sequence that selectively promotes the expression of several putative melanoma initiating cell markers...
May 24, 2017: ACS Central Science
Mioy T Huynh, S Jimena Mora, Matias Villalba, Marely E Tejeda-Ferrari, Paul A Liddell, Brian R Cherry, Anne-Lucie Teillout, Charles W Machan, Clifford P Kubiak, Devens Gust, Thomas A Moore, Sharon Hammes-Schiffer, Ana L Moore
Nature employs a TyrZ-His pair as a redox relay that couples proton transfer to the redox process between P680 and the water oxidizing catalyst in photosystem II. Artificial redox relays composed of different benzimidazole-phenol dyads (benzimidazole models His and phenol models Tyr) with substituents designed to simulate the hydrogen bond network surrounding the TyrZ-His pair have been prepared. When the benzimidazole substituents are strong proton acceptors such as primary or tertiary amines, theory predicts that a concerted two proton transfer process associated with the electrochemical oxidation of the phenol will take place...
May 24, 2017: ACS Central Science
Rochus Schmid
No abstract text is available yet for this article.
May 24, 2017: ACS Central Science
Aaron W Peters, Zhanyong Li, Omar K Farha
No abstract text is available yet for this article.
May 24, 2017: ACS Central Science
Alla Katsnelson
No abstract text is available yet for this article.
May 24, 2017: ACS Central Science
Mark Peplow
No abstract text is available yet for this article.
May 24, 2017: ACS Central Science
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