TY - JOUR A1 - Jedrusik-Bode, Monika A1 - Studencka, Maja A1 - Smolka, Christian A1 - Baumann, Tobias A1 - Schmidt, Henning A1 - Kampf, Jan A1 - Paap, Franziska A1 - Martin, Sophie A1 - Tazi, Jamal A1 - Müller, Kristian M. A1 - Krüger, Marcus A1 - Braun, Thomas A1 - Bober, Eva T1 - The sirtuin SIRT6 regulates stress granule formation in C. elegans and mammals JF - Journal of cell science N2 - SIRT6 is a NAD(+)-dependent deacetylase that modulates chromatin structure and safeguards genomic stability. Until now, SIRT6 has been assigned to the nucleus and only nuclear targets of SIRT6 are known. Here, we demonstrate that in response to stress, C. elegans SIR-2.4 and its mammalian orthologue SIRT6 localize to cytoplasmic stress granules, interact with various stress granule components and induce their assembly. Loss of SIRT6 or inhibition of its catalytic activity in mouse embryonic fibroblasts impairs stress granule formation and delays disassembly during recovery, whereas deficiency of SIR-2.4 diminishes maintenance of P granules and decreases survival of C. elegans under stress conditions. Our findings uncover a novel, evolutionary conserved function of SIRT6 in the maintenance of stress granules in response to stress. KW - C. elegans KW - G3BP KW - SIRT6 KW - Sirtuins KW - Stress KW - Stress granules Y1 - 2013 U6 - https://doi.org/10.1242/jcs.130708 SN - 0021-9533 SN - 1477-9137 VL - 126 IS - 22 SP - 5166 EP - + PB - Company of Biologists Limited CY - Cambridge ER - TY - JOUR A1 - Krüger, Tobias A1 - Linker, Torsten T1 - Synthesis of gamma-spirolactams by Birch reduction of arenes JF - European journal of organic chemistry N2 - A convenient method for the synthesis of gamma-spirolactams in only three steps is described. Birch reduction of inexpensive and commercially available aromatic carboxylic acids in the presence of chloroacetonitrile affords nitriles in moderate to good yields. Suitable precursors are methyl-substituted benzoic acids, naphthoic, and anthroic acid. Subsequent catalytic hydrogenation proceeds smoothly with PtO2 or Raney Ni as catalysts and lactams are isolated in excellent yields and stereoselectivities. Thus, up to 3 new stereogenic centers can be constructed as sole diastereomers from achiral benzoic acids. Furthermore, it is possible to control the degree of saturation at different pressures, affording products with 0, 1, or 2 double bonds. Overall, more than 15 new gamma-spirolactams have been synthesized in analytically pure form. KW - Arenes KW - Birch reduction KW - Hydrogenation KW - Lactams KW - Synthetic methods Y1 - 2021 U6 - https://doi.org/10.1002/ejoc.202100056 SN - 1099-0690 VL - 2021 IS - 10 SP - 1585 EP - 1591 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Krüger, Tobias A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Linker, Torsten T1 - Simple Synthesis of gamma-Spirolactams by Birch Reduction of Benzoic Acids JF - European journal of organic chemistry N2 - A convenient synthesis of gamma-spirolactams in only two steps was developed. Birch reduction of benzoic acids and immediate alkylation with chloroacetonitrile afforded cyclohexadienes in high yields. The products could be isolated by crystallization on a large scale in analytically pure form. Subsequent hydrogenation with platinum(IV) oxide as the catalyst reduced the nitrile functionality and the double bonds in the same step with excellent stereoselectivity. The relative configurations were determined unequivocally by X-ray analyses. Direct cyclization of the intermediary formed amino acids afforded the desired gamma-spirolactams in excellent overall yields. The procedure is characterized by few steps, cheap reagents, and can be performed on a large scale, interesting for industrial processes. KW - Diastereoselectivity KW - Hydrogenation KW - Lactams KW - Reduction KW - Synthetic methods Y1 - 2016 U6 - https://doi.org/10.1002/ejoc.201601650 SN - 1434-193X SN - 1099-0690 IS - 6 SP - 1074 EP - 1077 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Abdalla, Hassan E. A1 - Abramowski, Attila A1 - Aharonian, Felix A. A1 - Benkhali, Faiçal Ait A1 - Akhperjanian, A. G. A1 - Angüner, Ekrem Oǧuzhan A1 - Arrieta, M. A1 - Aubert, Pierre A1 - Backes, Michael A1 - Balzer, Arnim A1 - Barnard, Michelle A1 - Becherini, Yvonne A1 - Tjus, Julia Becker A1 - Berge, David A1 - Bernhard, Sabrina A1 - Bernlöhr, K. A1 - Birsin, E. A1 - Blackwell, R. A1 - Bottcher, Markus A1 - Boisson, Catherine A1 - Bolmont, J. A1 - Bordas, Pol A1 - Bregeon, Johan A1 - Brun, Francois A1 - Brun, Pierre A1 - Bryan, Mark A1 - Bulik, Tomasz A1 - Capasso, M. A1 - Carr, John A1 - Casanova, Sabrina A1 - Chakraborty, N. A1 - Chalme-Calvet, R. A1 - Chaves, Ryan C. G. A1 - Chen, Andrew A1 - Chevalier, J. A1 - Chretien, M. A1 - Colafrancesco, Sergio A1 - Cologna, Gabriele A1 - Condon, B. A1 - Conrad, Jan A1 - Couturier, C. A1 - Cui, Y. A1 - Davids, I. D. A1 - Degrange, B. A1 - Deil, Christoph A1 - deWilt, P. A1 - Djannati-Atai, Arache A1 - Domainko, Wilfried A1 - Donath, Axel A1 - Dubus, Guillaume A1 - Dutson, Kate A1 - Dyks, J. A1 - Dyrda, M. A1 - Edwards, T. A1 - Egberts, Kathrin A1 - Eger, P. A1 - Ernenwein, J. -P. A1 - Eschbach, S. A1 - Farnier, C. A1 - Fegan, Stuart A1 - Fernandes, M. V. A1 - Fiasson, A. A1 - Fontaine, G. A1 - Foerster, A. A1 - Funk, S. A1 - Füßling, Matthias A1 - Gabici, Stefano A1 - Gajdus, M. A1 - Gallant, Y. A. A1 - Garrigoux, T. A1 - Giavitto, Gianluca A1 - Giebels, B. A1 - Glicenstein, J. F. A1 - Gottschall, Daniel A1 - Goyal, A. A1 - Grondin, M. -H. A1 - Grudzinska, M. A1 - Hadasch, Daniela A1 - Hahn, J. A1 - Hawkes, J. A1 - Heinzelmann, G. A1 - Henri, Gilles A1 - Hermann, G. A1 - Hervet, Olivier A1 - Hillert, A. A1 - Hinton, James Anthony A1 - Hofmann, Werner A1 - Hoischen, Clemens A1 - Holler, M. A1 - Horns, D. A1 - Ivascenko, Alex A1 - Jacholkowska, A. A1 - Jamrozy, Marek A1 - Janiak, M. A1 - Jankowsky, D. A1 - Jankowsky, Felix A1 - Jingo, M. A1 - Jogler, Tobias A1 - Jouvin, Lea A1 - Jung-Richardt, Ira A1 - Kastendieck, M. A. A1 - Katarzynski, Krzysztof A1 - Katz, Uli A1 - Kerszberg, D. A1 - Khelifi, B. A1 - Kieffer, M. A1 - King, J. A1 - Klepser, S. A1 - Klochkov, Dmitry A1 - Kluzniak, W. A1 - Kolitzus, D. A1 - Komin, Nu. A1 - Kosack, K. A1 - Krakau, S. A1 - Kraus, Michael A1 - Krayzel, F. A1 - Kruger, P. P. A1 - Laffon, H. A1 - Lamanna, G. A1 - Lau, Jeanie A1 - Lees, J. -P. A1 - Lefaucheur, J. A1 - Lefranc, V. A1 - Lemiere, A. A1 - Lemoine-Goumard, M. A1 - Lenain, J. -P. A1 - Leser, Eva A1 - Lohse, Thomas A1 - Lorentz, M. A1 - Lui, R. A1 - Lypova, Iryna A1 - Marandon, Vincent A1 - Marcowith, Alexandre A1 - Mariaud, C. A1 - Marx, R. A1 - Maurin, G. A1 - Maxted, N. A1 - Mayer, Michael A1 - Meintjes, Petrus Johannes A1 - Menzler, U. A1 - Meyer, Manuel A1 - Mitchell, A. M. W. A1 - Moderski, R. A1 - Mohamed, M. A1 - Mora, K. A1 - Moulin, E. A1 - Murach, T. A1 - de Naurois, Mathieu A1 - Niederwanger, F. A1 - Niemiec, J. A1 - Oakes, L. A1 - Odaka, Hirokazu A1 - Ohm, Stefan A1 - Oettl, S. A1 - Ostrowski, M. A1 - Oya, I. A1 - Padovani, Marco A1 - Panter, M. A1 - Parsons, R. D. A1 - Arribas, M. Paz A1 - Pekeur, N. W. A1 - Pelletier, G. A1 - Petrucci, P. -O. A1 - Peyaud, B. A1 - Pita, S. A1 - Poon, Helen A1 - Prokhorov, Dmitry A1 - Prokoph, Heike A1 - Puehlhofer, Gerd A1 - Punch, Michael A1 - Quirrenbach, Andreas A1 - Raab, S. A1 - Reimer, Anita A1 - Reimer, Olaf A1 - Renaud, M. A1 - de los Reyes, R. A1 - Rieger, Frank A1 - Romoli, Carlo A1 - Rosier-Lees, S. A1 - Rowell, G. A1 - Rudak, B. A1 - Rulten, C. B. A1 - Sahakian, V. A1 - Salek, David A1 - Sanchez, David A. A1 - Santangelo, Andrea A1 - Sasaki, Manami A1 - Schlickeiser, Reinhard A1 - Schussler, F. A1 - Schulz, Andreas A1 - Schwanke, U. A1 - Schwemmer, S. A1 - Seyffert, A. S. A1 - Shafi, N. A1 - Simoni, R. A1 - Sol, H. A1 - Spanier, Felix A1 - Spengler, G. A1 - Spiess, F. A1 - Stawarz, Lukasz A1 - Steenkamp, R. A1 - Stegmann, Christian A1 - Stinzing, F. A1 - Stycz, K. A1 - Sushch, Iurii A1 - Tavernet, J. -P. A1 - Tavernier, T. A1 - Taylor, A. M. A1 - Terrier, R. A1 - Tluczykont, Martin A1 - Trichard, C. A1 - Tuffs, R. A1 - van der Walt, Johan A1 - van Eldik, Christopher A1 - van Soelen, Brian A1 - Vasileiadis, Georges A1 - Veh, J. A1 - Venter, C. A1 - Viana, A. A1 - Vincent, P. A1 - Vink, Jacco A1 - Voisin, F. A1 - Voelk, Heinrich J. A1 - Vuillaume, Thomas A1 - Wadiasingh, Z. A1 - Wagner, Stefan J. A1 - Wagner, P. A1 - Wagner, R. M. A1 - White, R. A1 - Wierzcholska, Alicja A1 - Willmann, P. A1 - Woernlein, A. A1 - Wouters, Denis A1 - Yang, R. A1 - Zabalza, Victor A1 - Zaborov, D. A1 - Zacharias, M. A1 - Zdziarski, A. A. A1 - Zech, Andreas A1 - Zefi, F. A1 - Ziegler, A. A1 - Zywucka, Natalia T1 - Search for Dark Matter Annihilations towards the Inner Galactic Halo from 10 Years of Observations with HESS JF - Physical review letters N2 - The inner region of the Milky Way halo harbors a large amount of dark matter (DM). Given its proximity, it is one of the most promising targets to look for DM. We report on a search for the annihilations of DM particles using gamma-ray observations towards the inner 300 pc of the Milky Way, with the H.E.S.S. array of ground-based Cherenkov telescopes. The analysis is based on a 2D maximum likelihood method using Galactic Center (GC) data accumulated by H.E.S.S. over the last 10 years (2004-2014), and does not show any significant gamma-ray signal above background. Assuming Einasto and Navarro-Frenk-White DM density profiles at the GC, we derive upper limits on the annihilation cross section . These constraints are the strongest obtained so far in the TeV DM mass range and improve upon previous limits by a factor 5. For the Einasto profile, the constraints reach values of 6 x 10(-26) cm(3) s(-1) in the W+W- channel for a DM particle mass of 1.5 TeV, and 2 x 10(-26) cm(3) s(-1) in the tau(+)tau(-) channel for a 1 TeV mass. For the first time, ground-based gamma-ray observations have reached sufficient sensitivity to probe values expected from the thermal relic density for TeV DM particles. Y1 - 2016 U6 - https://doi.org/10.1103/PhysRevLett.117.111301 SN - 0031-9007 SN - 1079-7114 VL - 117 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Krüger, Tobias A1 - Vorndran, Katja A1 - Linker, Torsten T1 - Regioselective arene functionalization : simple substitution of carboxylate by alkyl groups N2 - Arenes with various alkyl side-chains were synthesized in high yields and excellent regioselectivities. Starting from toluic and naphthoic acids, the carboxylate group was conveniently substituted by alkyl halides by Birch reduction and subsequent decarbonylation. The method is characterized by inexpensive starting materials and reagents, and methylation of arenes was realized. Besides simple alkyl substituents, the scope of arene functionalization was extended by benzyl, fluoro, amino, and ester groups. We were able to control the alkylation of 1-naphthoic acid during Birch reduction by the addition of tert-butanol. This allowed the regioselective synthesis of mono and bis-substituted naphthalenes from the same starting material. Y1 - 2009 UR - http://www3.interscience.wiley.com/cgi-bin/jhome/26293/ U6 - https://doi.org/10.1002/chem.200901774 SN - 0947-6539 ER - TY - JOUR A1 - Kleinpeter, Erich A1 - Heydenreich, Matthias A1 - Koch, Andreas A1 - Krtitschka, Angela A1 - Krüger, Tobias A1 - Linker, Torsten T1 - NMR spectroscopic conformational analysis of 4-methylene-cyclohexyl pivalateThe effect of sp(2) hybridization JF - Magnetic resonance in chemistry N2 - The conformational equilibrium of the axial/equatorial conformers of 4-methylene-cyclohexyl pivalate is studied by dynamic NMR spectroscopy in a methylene chloride/freon mixture. At 153K, the ring interconversion gets slow on the nuclear magnetic resonance timescale, the conformational equilibrium (-G degrees) can be examined, and the barrier to ring interconversion (G(#)) can be determined. The structural influence of sp(2) hybridization on both G degrees and G(#) of the cyclohexyl moiety can be quantified. KW - 4-methylene-cyclohexyl pivalate KW - conformational analysis KW - dynamic NMR spectroscopy KW - exo-methylene conformational effect at cyclohexane KW - quantum chemical calculations Y1 - 2017 U6 - https://doi.org/10.1002/mrc.4630 SN - 0749-1581 SN - 1097-458X VL - 55 SP - 1073 EP - 1078 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Neffe, Axel T. A1 - von Rüsten-Lange, Maik A1 - Braune, Steffen A1 - Lützow, Karola A1 - Roch, Toralf A1 - Richau, Klaus A1 - Krüger, Anne A1 - Becherer, Tobias A1 - Thünemann, Andreas F. A1 - Jung, Friedrich A1 - Haag, Rainer A1 - Lendlein, Andreas T1 - Multivalent grafting of hyperbranched oligo- and polyglycerols shielding rough membranes to mediate hemocompatibility JF - Journal of materials chemistry : B, Materials for biology and medicine N2 - Hemocompatible materials are needed for internal and extracorporeal biomedical applications, which should be realizable by reducing protein and thrombocyte adhesion to such materials. Polyethers have been demonstrated to be highly efficient in this respect on smooth surfaces. Here, we investigate the grafting of oligo- and polyglycerols to rough poly(ether imide) membranes as a polymer relevant to biomedical applications and show the reduction of protein and thrombocyte adhesion as well as thrombocyte activation. It could be demonstrated that, by performing surface grafting with oligo-and polyglycerols of relatively high polydispersity (>1.5) and several reactive groups for surface anchoring, full surface shielding can be reached, which leads to reduced protein adsorption of albumin and fibrinogen. In addition, adherent thrombocytes were not activated. This could be clearly shown by immunostaining adherent proteins and analyzing the thrombocyte covered area. The presented work provides an important strategy for the development of application relevant hemocompatible 3D structured materials. Y1 - 2014 U6 - https://doi.org/10.1039/c4tb00184b SN - 2050-750X SN - 2050-7518 VL - 2 IS - 23 SP - 3626 EP - 3635 PB - Royal Society of Chemistry CY - Cambridge ER - TY - GEN A1 - Neffe, Axel T. A1 - von Rüsten-Lange, Maik A1 - Braune, Steffen A1 - Lützow, Karola A1 - Roch, Toralf A1 - Richau, Klaus A1 - Krüger, Anne A1 - Becherer, Tobias A1 - Thünemann, Andreas F. A1 - Jung, Friedrich A1 - Haag, Rainer A1 - Lendlein, Andreas T1 - Multivalent grafting of hyperbranched oligo- and polyglycerols shielding rough membranes to mediate hemocompatibility N2 - Hemocompatible materials are needed for internal and extracorporeal biomedical applications, which should be realizable by reducing protein and thrombocyte adhesion to such materials. Polyethers have been demonstrated to be highly efficient in this respect on smooth surfaces. Here, we investigate the grafting of oligo- and polyglycerols to rough poly(ether imide) membranes as a polymer relevant to biomedical applications and show the reduction of protein and thrombocyte adhesion as well as thrombocyte activation. It could be demonstrated that, by performing surface grafting with oligo- and polyglycerols of relatively high polydispersity (>1.5) and several reactive groups for surface anchoring, full surface shielding can be reached, which leads to reduced protein adsorption of albumin and fibrinogen. In addition, adherent thrombocytes were not activated. This could be clearly shown by immunostaining adherent proteins and analyzing the thrombocyte covered area. The presented work provides an important strategy for the development of application relevant hemocompatible 3D structured materials. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 285 Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-99444 ER - TY - JOUR A1 - Fudickar, Werner A1 - Metz, Melanie A1 - Mai-Linde, Yasemin A1 - Krüger, Tobias A1 - Kelling, Alexandra A1 - Sperlich, Eric A1 - Linker, Torsten T1 - Influence of functional groups on the ene reaction of singlet oxygen with 1,4-cyclohexadienes JF - Photochemistry and photobiology : the official journal of the American Society for Photobiology N2 - The photooxygenation of 1,4-cyclohexadienes has been studied with a special focus on regio- and stereoselectivities. In all examples, only the methyl-substituted double bond undergoes an ene reaction with singlet oxygen, to afford hydroperoxides in moderate to good yields. We explain the high regioselectivities by a "large-group effect" of the adjacent quaternary stereocenter. Nitriles decrease the reactivity of singlet oxygen, presumably by quenching, but can stabilize proposed per-epoxide intermediates by polar interactions resulting in different stereoselectivities. Spiro lactams and lactones show an interesting effect on regio- and stereoselectivities of the ene reactions. Thus, singlet oxygen attacks the double bond preferentially anti to the carbonyl group, affording only one regioisomeric hydroperoxide. If the reaction occurs from the opposite face, the other regioisomer is exclusively formed by severe electrostatic repulsion in a perepoxide intermediate. We explain this unusual behavior by the fixed geometry of spiro compounds and call it a "spiro effect" in singlet oxygen ene reactions. Y1 - 2021 U6 - https://doi.org/10.1111/php.13422 SN - 0031-8655 SN - 1751-1097 VL - 97 IS - 6 SP - 1289 EP - 1297 PB - Wiley CY - Malden, Mass. ER - TY - JOUR A1 - Kumke, Michael Uwe A1 - Eidner, Sascha A1 - Krüger, Tobias T1 - Fluorescence quenching and luminescence sensitization in complexes of Tb3+ and Eu3+ with humic substances N2 - Intrinsic fluorescence quenching of humic substances (HS) and the sensitization of Ln(3+) luminescence (Ln3+ Tb3+, Eu3+) in HS complexes were investigated. Both measurements yielded complementary information on the complexation of metals by HS. Large differences between fulvic acids(FA)and humic acids (HA) were found. From time-resolved luminescence measurements it is concluded that a combination of energy transfer and energy back transfer between HS and Ln(3+) is responsible for the observed luminescence decay characteristics. In the case of Eu3+, an additional participation of charge-transfer states is suggested. A new concept for the evaluation of the sensitized luminescence decays of Ln(3+) was adapted Y1 - 2005 ER -