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  • American Association for the Advancement of Science (AAAS)  (3)
  • 2010-2014  (3)
  • 1
    Publication Date: 2013-08-31
    Description: Trojan objects share a planet's orbit, never straying far from the triangular Lagrangian points, 60 degrees ahead of (L4) or behind (L5) the planet. We report the detection of a Uranian Trojan; in our numerical integrations, 2011 QF99 oscillates around the Uranian L4 Lagrange point for 〉70,000 years and remains co-orbital for ~1 million years before becoming a Centaur. We constructed a Centaur model, supplied from the transneptunian region, to estimate temporary co-orbital capture frequency and duration (to a factor of 2 accuracy), finding that at any time 0.4 and 2.8% of the population will be Uranian and Neptunian co-orbitals, respectively. The co-orbital fraction (~2.4%) among Centaurs in the International Astronomical Union Minor Planet Centre database is thus as expected under transneptunian supply.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Alexandersen, Mike -- Gladman, Brett -- Greenstreet, Sarah -- Kavelaars, J J -- Petit, Jean-Marc -- Gwyn, Stephen -- New York, N.Y. -- Science. 2013 Aug 30;341(6149):994-7. doi: 10.1126/science.1238072.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, Canada. mikea@astro.ubc.ca〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23990557" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2014-07-06
    Description: Activation of the small guanosine triphosphatase H-Ras by the exchange factor Son of Sevenless (SOS) is an important hub for signal transduction. Multiple layers of regulation, through protein and membrane interactions, govern activity of SOS. We characterized the specific activity of individual SOS molecules catalyzing nucleotide exchange in H-Ras. Single-molecule kinetic traces revealed that SOS samples a broad distribution of turnover rates through stochastic fluctuations between distinct, long-lived (more than 100 seconds), functional states. The expected allosteric activation of SOS by Ras-guanosine triphosphate (GTP) was conspicuously absent in the mean rate. However, fluctuations into highly active states were modulated by Ras-GTP. This reveals a mechanism in which functional output may be determined by the dynamical spectrum of rates sampled by a small number of enzymes, rather than the ensemble average.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4255705/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4255705/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Iversen, Lars -- Tu, Hsiung-Lin -- Lin, Wan-Chen -- Christensen, Sune M -- Abel, Steven M -- Iwig, Jeff -- Wu, Hung-Jen -- Gureasko, Jodi -- Rhodes, Christopher -- Petit, Rebecca S -- Hansen, Scott D -- Thill, Peter -- Yu, Cheng-Han -- Stamou, Dimitrios -- Chakraborty, Arup K -- Kuriyan, John -- Groves, Jay T -- P01 AI091580/AI/NIAID NIH HHS/ -- R01 AI104789/AI/NIAID NIH HHS/ -- Howard Hughes Medical Institute/ -- New York, N.Y. -- Science. 2014 Jul 4;345(6192):50-4. doi: 10.1126/science.1250373.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA. ; Department of Chemical Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA. ; Howard Hughes Medical Institute, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA. ; Department of Mechanical Engineering, University of California, Berkeley, Berkeley, CA 94720, USA. ; Department of Chemistry, MIT, Cambridge, MA 02139, USA. ; Mechanobiology Institute, National University of Singapore, Singapore. ; Department of Chemistry and Nano-Science Center, University of Copenhagen, Copenhagen, Denmark. ; Department of Chemical Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA. Department of Chemistry, MIT, Cambridge, MA 02139, USA. Department of Biological Engineering, MIT, Cambridge, MA 02139, USA. Ragon Institute of Massachusetts General Hospital, MIT, and Harvard, Cambridge, MA 02139, USA. Department of Physics, MIT, Cambridge, MA 02139, USA. Institute for Medical Engineering and Science, MIT, Cambridge, MA 02139, USA. ; Howard Hughes Medical Institute, Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA. Howard Hughes Medical Institute, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA. Physical Biosciences and Materials Sciences Divisions, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. ; Howard Hughes Medical Institute, Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA. Mechanobiology Institute, National University of Singapore, Singapore. Physical Biosciences and Materials Sciences Divisions, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. Berkeley Education Alliance for Research in Singapore, 1 Create Way, CREATE tower level 11, University Town, Singapore 138602. jtgroves@lbl.gov.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24994643" target="_blank"〉PubMed〈/a〉
    Keywords: Allosteric Regulation ; Catalytic Domain ; Crystallography, X-Ray ; Enzyme Activation ; Humans ; Kinetics ; Nucleotides/chemistry ; *Protein Interaction Domains and Motifs ; Proto-Oncogene Proteins p21(ras)/*agonists ; Son of Sevenless Protein, Drosophila/*chemistry/genetics
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2014-09-27
    Description: Ozonolysis of alkenes, an important nonphotolytic source of hydroxyl (OH) radicals in the troposphere, proceeds through energized Criegee intermediates that undergo unimolecular decay to produce OH radicals. Here, we used infrared (IR) activation of cold CH3CHOO Criegee intermediates to drive hydrogen transfer from the methyl group to the terminal oxygen, followed by dissociation to OH radicals. State-selective excitation of CH3CHOO in the CH stretch overtone region combined with sensitive OH detection revealed the IR spectrum of CH3CHOO, effective barrier height for the critical hydrogen transfer step, and rapid decay dynamics to OH products. Complementary theory provides insights on the IR overtone spectrum, as well as vibrational excitations, structural changes, and energy required to move from the minimum-energy configuration of CH3CHOO to the transition state for the hydrogen transfer reaction.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Liu, Fang -- Beames, Joseph M -- Petit, Andrew S -- McCoy, Anne B -- Lester, Marsha I -- New York, N.Y. -- Science. 2014 Sep 26;345(6204):1596-8. doi: 10.1126/science.1257158.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA. ; Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210-1173, USA. ; Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA. milester@sas.upenn.edu.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25258077" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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