6.6 Messparameter der ESR-Experimente
6.6.4 Cw-ESR-Messungen
Alle cw-Messungen wurden bei einer Modulationsfrequenz von 100 kHz auf-genommen. F¨ur Tieftemperaturexperimente wurde der Kryostat des Typs CF935 (Firma Oxford Instruments) verwendet.
Abb. Spektrometer Resonator Frequenz T [K] Lichtquelle Modulations- Leistung amplitude [G] [mW]
4.6 MiniScope – X 293 – 0,5 0,0032
MS200
4.7 MiniScope – X 293 – 0,5 0,0032
MS200
4.8 ELEXSYS ER4118X X 120 – 2 0,0013
E580 MS3
5.3 ELEXSYS ER4118X X 70 ExciStarXS 5 0,2002
E580 MS3 500
5.15 ELEXSYS EN4118X X 70 LAX1000 10 2
E580 MD4
5.18 ELEXSYS EN5107D2 Q 70 LAX1000 9,95 0,0962
E580
6.11 MiniScope – X 293 – 0,5 0,0032
MS200
Tabelle 6.6: Parameter f¨ur cw-ESR-Messungen.
At GLOW TIME we’re a Do It!...
freezing temperatures, we knew it...
we take a shinin’ to it...
Addams Family
Kapitel 7
Zusammenfassung
Moderne, etablierte ESR-Methoden zur Abstandsmessung von ortsspezifisch eingebrachten Spinmarkern sind insbesondere in der Biostrukturforschung
¨außerst erfolgreich. Die in dieser Arbeit vorgestellten methodischen Entwick-lungen werden dazu beitragen, den Anwendungsbereich weiter auszudehnen.
Ein in der ESR-Spektroskopie bisher nicht verwendeter, modellbasierter An-satz zur Analyse von Abstandsverteilungen konnte in Kapitel 3 vorgeschlagen werden, um die Flexibilit¨at des Spinmarkerlinkers ber¨ucksichtigen zu k¨onnen, auch wenn kein Strukturmodell des zu untersuchenden Molek¨uls vorliegt.
Dabei wird erstmals bedacht, dass der wahrscheinlichste Spinmarkerabstand nicht mit dem Abstand zwischen den wahrscheinlichsten Spinmarkerpositio-nen ¨ubereinstimmt. Das Potential des Ansatzes konnte mittels numerischer Daten, molekulardynamischer Simulationen und experimentell belegt wer-den.
Dieser neue Ansatz wurde in einer Studie zum intrazellul¨aren mechanischen Energietransfer verwendet, die in Kapitel 4 beschrieben wurde. Das unter-suchte Protein TonB spielt eine Rolle bei der N¨ahrstoffaufnahme gramnega-tiver Bakterien. ¨Uber die ESR-Messungen konnte erstmals gezeigt werden, dass TonB das Periplasma des Bakteriums zu ¨uberbr¨ucken vermag, w¨ahrend es eine PolyprolinII-Struktur aufweist. Diese Erkenntnisse haben dazu beige-tragen, ein Modell auszuarbeiten, wie Energie von der inneren zur ¨außeren Membran gelangen kann. Die Energie¨ubertragung ist unabdingbar f¨ur die Aufnahme von N¨ahrstoffen, die an der ¨außeren Membran zur Verf¨ugung ste-hen.
123
124 7. ZUSAMMENFASSUNG Kernst¨uck der Arbeit ist die Entwicklung von Ans¨atzen zur Abstandsmes-sung unter Verwendung eines optisch adressierbaren Spinmarkers.
Kapitel 5 gibt eine Einf¨uhrung in Singulett-Triplett-Systeme, die die Grund-lage optisch adressierbarer Spinmarker bilden. Die Wahl eines Molek¨uls, das die Rahmenbedingungen eines Spinmarkers erf¨ullt, wird auf Grundlage einer UV- und ESR-spektroskopischen Charakterisierung getroffen. F¨ur die ESR-Experimente konnte die Einkopplung der Lichtquellen zur Anregung in den Mikrowellenresonator, der sich in einem Heliumkryostaten befindet, sowie die Synchronisation der Mikrowellen- und Laserpulse gel¨ost werden.
Erstmals ist unter Verwendung eines optisch schaltbaren Singulett-Triplett-Systems und einem persistenten Radikal eine Abstandsbestimmung in einem Modellsystem gelungen. Dabei wird ein laserangeregtes Anthracenmolek¨ul beobachtet und dessen Dipol-Dipol-Wechselwirkung zu einem Nitroxid-Spin-marker gemessen. Die gefundene Abstandsverteilung ist in guter ¨ Uberein-stimmung mit Vorhersagen, die ¨uber Rotamerberechnungen an einem Struk-turmodell getroffen wurden. Mit diesem Ansatz sind nun Abstandsmessungen zwischen selektiv schaltbaren Markern m¨oglich.
Vorgeschlagen wird ein neues Experiment zur Abstandsmessung mittels dy-namischen Schaltens des optisch adressierbaren Markers, das LaserIMD (La-ser Induced Magnetic Dipole)-Experiment. Der zug¨angliche Abstandsbereich herk¨ommlicher gepulster ESR-Methoden von 1,5 nm bis 10 nm k¨onnte ¨uber die erwartete Verbesserung im Signal-zu-Rausch-Verh¨altnis des LaserIMD-Experiments auf bis zu 16 nm erh¨oht werden.
Mit grundlegenden Messungen sind nun die Voraussetzungen f¨ur dieses Ex-periment gelegt, so dass nun Kriterien f¨ur ein maßgeschneidertes Singulett-Triplett-System aufgestellt werden konnten.
Von der Mehrzahl der Werke bleiben nur die Zitate ¨ubrig.
Ist es dann nicht besser, von Anfang an nur die Zitate aufzuschreiben?
Stanislaw Jerzy Lec
Literaturverzeichnis
[1] W. L. Hubbell and C. Altenbach, “Investigation of structure and dyna-mics in membrane-proteins using site-directed spin-labeling,” Current Opinion in Structural Biology, vol. 4, pp. 566–573, 1994.
[2] W. L. Hubbell, A. Gross, R. Langen, and M. A. Lietzow, “Recent advances in site-directed spin labeling of proteins,” Current Opinion in Structural Biology, vol. 8, pp. 649–656, 1998.
[3] M. Azarkh, O. Okle, V. Singh, I. T. Seemann, J. S. Hartig, D. R.
Dietrich, and M. Drescher, “Long-range distance determination in a DNA model system inside xenopus laevis oocytes by in-cell spin-label EPR,” ChemBioChem, vol. 12, no. 13, pp. 1992–5, 2011.
[4] M. Azarkh, V. Singh, O. Okle, D. R. Dietrich, J. S. Hartig, and M. Dre-scher, “Intracellular conformations of human telomeric quadruplexes studied by electron paramagnetic resonance spectroscopy,” ChemPhy-sChem, vol. 13, no. 6, pp. 1444–7, 2012.
[5] G. Likhtenshtein,Nitroxides: Applications in Chemistry, Biomedicine, and Materials Science. Wiley-VCH, 2008.
[6] J. P. Klare and H. J. Steinhoff, “Spin labeling EPR,” Photosynthesis Research, vol. 102, pp. 377–390, 2009.
[7] R. S. Alexander, S. K. Nair, and D. W. Christianson, “Engineering the hydrophobic pocket of carbonic anhydrase-II,” Biochemistry, vol. 30, no. 46, pp. 11064–11072, 1991.
[8] H. S. Mchaourab, M. A. Lietzow, K. Hideg, and W. L. Hubbell, “Motion of spin-labeled side chains in T4 lysozyme, correlation with protein structure and dynamics,”Biochemistry, vol. 35, no. 24, pp. 7692–7704, 1996.
127
128 LITERATURVERZEICHNIS [9] A. Potapov, H. Yagi, T. Huber, S. Jergic, N. E. Dixon, G. Otting, and D. Goldfarb, “Nanometer-scale distance measurements in proteins using Gd3+ spin labeling,”Journal of the American Chemical Society, vol. 132, pp. 9040–9048, 2010.
[10] M. E. Pandelia, H. Ogata, and W. Lubitz, “Intermediates in the cata-lytic cycle of [NiFe] hydrogenase: Functional spectroscopy of the active site,” ChemPhysChem, vol. 11, no. 6, pp. 1127–1140, 2010.
[11] M. Drescher, EPR Spectroscopy: Applications in Chemistry and Biolo-gy, vol. 321. Berlin: Springer, 2012. p. 91 to 120, M. Drescher and G.
Jeschke.
[12] S. Stoll and A. Schweiger, “EasySpin, a comprehensive software packa-ge for spectral simulation and analysis in EPR,” Journal of Magnetic Resonance, vol. 178, pp. 42–55, 2006.
[13] A. D. Milov, A. B. Ponomarev, and Y. D. Tsvetkov, “Electron electron double-resonance in electron-spin echo - model biradical systems and the sensitized photolysis of decalin,”Chemical Physics Letters, vol. 110, no. 1, pp. 67–72, 1984.
[14] G. Jeschke, “Distance measurements in the nanometer range by pulse EPR,” ChemPhysChem, vol. 3, pp. 927–932, 2002.
[15] G. Jeschke, “Determination of the nanostructure of polymer materi-als by electron paramagnetic resonance spectroscopy,”Macromolecular Rapid Communications, vol. 23, no. 4, pp. 227–246, 2002.
[16] G. Jeschke, “DEER distance measurements on proteins,” Annual Re-view of Physical Chemistry, vol. 63, pp. 419–46, 2012.
[17] S. Milikisyants, F. Scarpelli, M. G. Finiguerra, M. Ubbink, and M. Hu-ber, “A pulsed EPR method to determine distances between parama-gnetic centers with strong spectral anisotropy and radicals: The dead-time free RIDME sequence,”Journal of Magnetic Resonance, vol. 201, no. 1, pp. 48–56, 2009.
[18] R. Ward, A. Bowman, E. Sozudogru, H. El-Mkami, T. Owen-Hughes, and D. G. Norman, “EPR distance measurements in deuterated prote-ins,” Journal of Magnetic Resonance, vol. 207, no. 1, pp. 164–7, 2010.
LITERATURVERZEICHNIS 129 [19] O. Schiemann, P. Cekan, D. Margraf, T. F. Prisner, and S. T. Sigurds-son, “Relative orientation of rigid nitroxides by PELDOR: beyond di-stance measurements in nucleic acids,” Angewandte Chemie- Interna-tional Edition, vol. 48, no. 18, pp. 3292–5, 2009.
[20] A. P. Todd, J. Cong, F. Levinthal, C. Levinthal, and W. L. Hubbell,
“Site-directed mutagenesis of colicin E1 provides specific attachment sites for spin labels whose spectra are sensitive to local conformation,”
Proteins-Structure Function and Bioinformatics, vol. 6, no. 3, pp. 294–
305, 1989.
[21] A. Schweiger and G. Jeschke,Principles of pulse electron paramagnetic resonance. Oxford: Oxford University Press, reprinted 2005 ed., 2005.
[22] M. Pannier, S. Veit, A. Godt, G. Jeschke, and H. W. Spiess, “Dead-time free measurement of dipole-dipole interactions between electron spins,” Journal of Magnetic Resonance, vol. 142, pp. 331–340, 2000.
[23] M. Lindgren, G. R. Eaton, S. S. Eaton, B. H. Jonsson, P. Hammar-strom, M. Svensson, and U. Carlsson, “Electron spin echo decay as a probe of aminoxyl environment in spin-labeled mutants of human carbonic anhydrase II,” Journal of the Chemical Society-Perkin Tran-sactions 2, no. 12, pp. 2549–2554, 1997.
[24] Bruker, Almanac 2012. Bruker Corporation, 2012.
[25] G. Jeschke and Y. Polyhach, “Distance measurements on spin-labelled biomacromolecules by pulsed electron paramagnetic resonance,” Phy-sical Chemistry Chemical Physics, vol. 9, pp. 1895–1910, 2007.
[26] G. Jeschke, “DeerAnalysis2011 user manual,”
http://www.epr.ethz.ch/software/index Accessed 7 April 2011, 2011.
[27] G. Jeschke, H. Zimmermann, and A. Godt, “Isotope selection in distan-ce measurements between nitroxides,”Journal of Magnetic Resonance, vol. 180, no. 1, pp. 137–146, 2006.
[28] A. N. Tikhonov and V. I. Arsenin, Solutions of ill-posed problems.
Scripta series in mathematics, Washington New York: Winston ; dis-tributed solely by Halsted Press, 1977.
[29] Y. Polyhach, E. Bordignon, and G. Jeschke, “Rotamer libraries of spin labelled cysteines for protein studies,” Physical Chemistry Chemical Physics, vol. 13, no. 6, pp. 2356–2366, 2011.
130 LITERATURVERZEICHNIS [30] H. Jager, A. Koch, V. Maus, H. W. Spiess, and G. Jeschke, “Relaxation-based distance measurements between a nitroxide and a lanthanide spin label,” Journal of Magnetic Resonance, vol. 194, no. 2, pp. 254–263, 2008.
[31] P. Lueders, G. Jeschke, and M. Yulikov, “Double electron-electron re-sonance measured between Gd3+ ions and nitroxide radicals,”Journal of Physical Chemistry Letters, vol. 2, no. 6, pp. 604–609, 2011.
[32] M. Lorenzi, C. Puppo, R. Lebrun, S. Lignon, V. Roubaud, M. Martin-ho, E. Mileo, P. Tordo, S. R. A. Marque, B. Gontero, B. Guigliarelli, and V. Belle, “Tyrosine-targeted spin labeling and EPR spectroscopy:
An alternative strategy for studying structural transitions in proteins,”
Angewandte Chemie-International Edition, vol. 50, no. 39, pp. 9108–
9111, 2011.
[33] N. Barhate, P. Cekan, A. P. Massey, and S. T. Sigurdsson, “A nucleosi-de that contains a rigid nitroxinucleosi-de spin label: a fluorophore in disguise,”
Angew Chem Int Ed Engl, vol. 46, no. 15, pp. 2655–8, 2007.
[34] M. Azarkh, O. Okle, P. Eyring, D. R. Dietrich, and M. Drescher, “Eva-luation of spin labels for in-cell EPR by analysis of nitroxide reduction in cell extract of Xenopus laevis oocytes,” Journal of Magnetic Reso-nance, vol. 212, no. 2, pp. 450–454, 2011.
[35] A. Carrington and A. D. McLachlan, Introduction to magnetic reso-nance with applications to chemistry and chemical physics. Harper’s chemistry series, New York,: Harper and Row, 1967.
[36] S. Mc Glynn, T. Azumi, and M. Kinoshita, Molecular spectroscopy of the triplet state. New Jersey: Prentice-Hall, Inc., 1969.
[37] J. H. van der Waals, “EPR of photo-excited triplet states: a personal account,” Applied Magnetic Resonance, vol. 20, no. 4, pp. 545–561, 2001.
[38] H. Haken and H. Wolf,Molek¨ulphysik und Quantenchemie: Einf¨uhrung in die experimentellen und theoretischen Grundlagen. Springer, 2006.
[39] H. Levanon and J. R. Norris, “Photoexcited triplet-state and photo-synthesis,” Chemical Reviews, vol. 78, no. 3, pp. 185–198, 1978.
[40] C. A. Hutchison and B. W. Mangum, “Paramagnetic resonance absorp-tion in Naphthalene in its phosphorescent state,”Journal of Chemical Physics, vol. 29, no. 4, pp. 952–953, 1958.
LITERATURVERZEICHNIS 131 [41] D. Carbonera, “Optically detected magnetic resonance (ODMR) of photoexcited triplet states,”Photosynthesis Research, vol. 102, no. 2-3, pp. 403–414, 2009.
[42] P. A. Lane, L. S. Swanson, Q. X. Ni, J. Shinar, J. P. Engel, T. J.
Barton, and L. Jones, “Dynamics of photoexcited states in C-60 - an optically detected magnetic-resonance, ESR, and light-induced ESR study,”Physical Review Letters, vol. 68, no. 6, pp. 887–890, 1992.
[43] G. Vonbunau, S. Weber, and T. Wolff, “Time and temperature-dependence of anthracene triplet yields in frozen aqueous micellar so-lutions - an electron-paramagnetic-resonance study,”Journal of Photo-chemistry and Photobiology a-Chemistry, vol. 80, no. 1-3, pp. 363–368, 1994.
[44] J. L. Sessler, M. Sathiosatham, C. T. Brown, T. A. Rhodes, and G. Wie-derrecht, “Hydrogen-bond-mediated photoinduced electron-transfer:
novel dimethylaniline-anthracene ensembles formed via Watson-Crick base-pairing,” Journal of the American Chemical Society, vol. 123, no. 16, pp. 3655–60, 2001.
[45] D. Eliezer, “Biophysical characterization of intrinsically disordered pro-teins,”Current Opinion in Structural Biology, vol. 19, pp. 23–30, 2009.
[46] M. Pannier, M. Schops, V. Schadler, U. Wiesner, G. Jeschke, and H. W.
Spiess, “Characterization of ionic clusters in different ionically functio-nalized diblock copolymers by cw EPR and four-pulse double electron-electron resonance,” Macromolecules, vol. 34, pp. 5555–5560, 2001.
[47] G. Jeschke, G. Panek, A. Godt, A. Bender, and H. Paulsen, “Data analysis procedures for pulse ELDOR measurements of broad distance distributions,”Applied Magnetic Resonance, vol. 26, pp. 223–244, 2004.
[48] Y. W. Chiang, P. P. Borbat, and J. H. Freed, “The determination of pair distance distributions by pulsed ESR using Tikhonov regulariza-tion,” Journal of Magnetic Resonance, vol. 172, pp. 279–295, 2005.
[49] M. Drescher, G. Veldhuis, B. D. van Rooijen, S. Milikisyants, V. Sub-ramaniam, and M. Huber, “Antiparallel arrangement of the helices of vesicle-bound alpha-synuclein,”Journal of the American Chemical So-ciety, vol. 130, pp. 7796–7797, 2008.
132 LITERATURVERZEICHNIS [50] G. N. Murshudov, A. A. Vagin, and E. J. Dodson, “Refinement of macromolecular structures by the maximum-likelihood method,” Acta Crystallogr D Biol Crystallogr, vol. 53, no. Pt 3, pp. 240–55, 1997.
[51] P. H. Zwart and V. S. Lamzin, “Distance distributions and electron-density characteristics of protein models,”Acta Crystallogr D Biol Cry-stallogr, vol. 59, no. Pt 12, pp. 2104–13, 2003.
[52] L. S. Churchman, H. Flyvbjerg, and J. A. Spudich, “A non-Gaussian distribution quantifies distances measured with fluorescence localizati-on techniques,” Biophysical Journal, vol. 90, no. 2, pp. 668–71, 2006.
[53] J. Antelman, C. Wilking-Chang, S. Weiss, and X. Michalet, “Nanome-ter distance measurements between multicolor quantum dots,” Nano Letters, vol. 9, no. 5, pp. 2199–205, 2009.
[54] H. Gudbjartsson and S. Patz, “The Rician distribution of noisy MRI data,”Magnetic Resonance in Medicine, vol. 34, no. 6, pp. 910–4, 1995.
[55] A. J. den Dekker and J. Sijbers, “Implications of the Rician distribu-tion for fMRI generalized likelihood ratio tests,” Magnetic Resonance Imaging, vol. 23, no. 9, pp. 953–9, 2005.
[56] S. Domingo K¨ohler, M. Spitzbarth, K. Diederichs, T. E. Exner, and M. Drescher, “A short note on the analysis of distance measurements by electron paramagnetic resonance,”Journal of Magnetic Resonance, vol. 208, pp. 167–170, 2011.
[57] K. S. Miller, Gaussian Distributions. New York: Wiley ans Sons, 1964.
[58] D. A. Case, T. A. Darden, T. E. Cheatham, C. L. Simmerling, J. Wang, R. E. Duke, R. Luo, R. C. Walker, W. Zhang, K. M. Merz, V. Roberts, S. Hayik, A. Roitberg, G. Seabra, J. Swails, A. W. Goetz, I. Kolossvai, K. F. Wong, F. Paesani, J. Vanicek, R. M. Wolf, J. Liu, X. Wu, S. R.
Brozell, T. Steinbrecher, H. Gohlke, Q. Cai, X. Ye, J. Wang, M.-J.
Hsieh, G. Cui, V. Roe, D. H. Mathews, M. G. Seetin, R. Salomon-Ferrer, C. Sagui, V. Babin, T. Luchko, V. Gusarov, A. Kovalenko, and V. Kollman, “Amber 12,” 2008.
[59] G. Shanmugam and P. L. Polavarapu, “Structural transition during thermal denaturation of collagen in the solution and film states,” Chi-rality, vol. 21, no. 1, pp. 152–159, 2009.
LITERATURVERZEICHNIS 133 [60] M. Kuemin, S. Schweizer, C. Ochsenfeld, and H. Wennemers, “Effects of terminal functional groups on the stability of the polyproline II struc-ture: a combined experimental and theoretical study,” Journal of the American Chemical Society, vol. 131, no. 42, pp. 15474–82, 2009.
[61] M. Mutter, T. Wohr, S. Gioria, and M. Keller, “Pseudo-prolines: induc-tion of cis/trans-conformainduc-tional interconversion by decreased transiinduc-tion state barriers,” Biopolymers, vol. 51, no. 2, pp. 121–8, 1999.
[62] A. A. Adzhubei and M. J. E. Sternberg, “Left-handed polyproline-II helices commonly occur in globular-proteins,”Journal of Molecular Biology, vol. 229, no. 2, pp. 472–493, 1993.
[63] S. Kakinoki, Y. Hirano, and M. Oka, “On the stability of polyproline-I and II structures of proline oligopeptides,” Polymer Bulletin, vol. 53, no. 2, pp. 109–115, 2005.
[64] H. F. Yuan, T. Xia, B. Schuler, and M. Orrit, “Temperature-cycle single-molecule FRET microscopy on polyprolines,” Physical Che-mistry Chemical Physics, vol. 13, no. 5, pp. 1762–1769, 2011.
[65] B. Schuler, E. A. Lipman, P. J. Steinbach, M. Kumke, and W. A. Eaton,
“Polyproline and the spectroscopic ruler revisited with single-molecule fluorescence,” Proceedings of the National Academy of Sciences of the United States of America, vol. 102, no. 8, pp. 2754–2759, 2005.
[66] B. K. Kay, M. P. Williamson, and M. Sudol, “The importance of being proline: the interaction of proline-rich motifs in signaling proteins with their cognate domains,”Faseb Journal, vol. 14, no. 2, pp. 231–41, 2000.
[67] G. Jeschke, V. Chechik, P. Ionita, A. Godt, H. Zimmermann, J. Ban-ham, C. R. Timmel, D. Hilger, and H. Jung, “DeerAnalysis2006 - a comprehensive software package for analyzing pulsed ELDOR data,”
Applied Magnetic Resonance, vol. 30, pp. 473–498, 2006.
[68] C. C. Wang and A. Newton, “An additional step in the transport of iron defined by the TonB locus of Escherichia coli,” Journal of Biological Chemistry, vol. 246, no. 7, pp. 2147–51, 1971.
[69] C. N. Cornelissen, G. D. Biswas, J. Tsai, D. K. Paruchuri, S. A. Thomp-son, and P. F. Sparling, “Gonococcal transferrin-binding protein 1 is re-quired for transferrin utilization and is homologous to TonB-dependent outer membrane receptors,” Journal of Bacteriology, vol. 174, no. 18, pp. 5788–97, 1992.
134 LITERATURVERZEICHNIS [70] P. I. Higgs, R. A. Larsen, and K. Postle, “Quantification of known components of the Escherichia coli TonB energy transduction system:
TonB, ExbB, ExbD and FepA,”Molecular Microbiology, vol. 44, no. 1, pp. 271–81, 2002.
[71] R. A. Larsen, T. E. Letain, and K. Postle, “In vivo evidence of TonB shuttling between the cytoplasmic and outer membrane in Escherichia coli,”Molecular Microbiology, vol. 49, no. 1, pp. 211–8, 2003.
[72] C. Chang, A. Mooser, A. Pluckthun, and A. Wlodawer, “Crystal struc-ture of the dimeric C-terminal domain of TonB reveals a novel fold,”
Journal of Biological Chemistry, vol. 276, no. 29, pp. 27535–40, 2001.
[73] V. Braun, S. Gaisser, C. Herrmann, K. Kampfenkel, H. Killmann, and I. Traub, “Energy-coupled transport across the outer membrane of Escherichia coli: ExbB binds ExbD and TonB in vitro, and leucine 132 in the periplasmic region and aspartate 25 in the transmembra-ne region are important for ExbD activity,” Journal of Bacteriology, vol. 178, no. 10, pp. 2836–45, 1996.
[74] P. I. Higgs, P. S. Myers, and K. Postle, “Interactions in the TonB-dependent energy transduction complex: ExbB and ExbD form homo-multimers,”Journal of Bacteriology, vol. 180, no. 22, pp. 6031–8, 1998.
[75] M. Kim, G. E. Fanucci, and D. S. Cafiso, “Substrate-dependent trans-membrane signaling in TonB-dependent transporters is not conserved,”
Proceedings of the National Academy of Science USA, vol. 104, no. 29, pp. 11975–80, 2007.
[76] P. D. Pawelek, N. Croteau, C. Ng-Thow-Hing, C. M. Khursigara, N. Moiseeva, M. Allaire, and J. W. Coulton, “Structure of TonB in complex with FhuA, E. coli outer membrane receptor,” Science, vol. 312, no. 5778, pp. 1399–402, 2006.
[77] E. Cascales, R. Lloubes, and J. N. Sturgis, “The TolQ-TolR proteins energize TolA and share homologies with the flagellar motor proteins MotA-MotB,”Molecular Microbiology, vol. 42, no. 3, pp. 795–807, 2001.
[78] J. Gumbart, M. C. Wiener, and E. Tajkhorshid, “Mechanics of force propagation in TonB-dependent outer membrane transport,” Biophy-sical Journal, vol. 93, no. 2, pp. 496–504, 2007.
[79] L. L. Graham, R. Harris, W. Villiger, and T. J. Beveridge, “Freeze-substitution of gram-negative eubacteria: general cell morphology and
LITERATURVERZEICHNIS 135 envelope profiles,”Journal of Bacteriology, vol. 173, no. 5, pp. 1623–33, 1991.
[80] J. S. Evans, B. A. Levine, I. P. Trayer, C. J. Dorman, and C. F. Higgins,
“Sequence-imposed structural constraints in the TonB protein of E.
coli,” FEBS Letters, vol. 208, no. 2, pp. 211–6, 1986.
[81] S. Brewer, M. Tolley, I. P. Trayer, G. C. Barr, C. J. Dorman, K. Han-navy, C. F. Higgins, J. S. Evans, B. A. Levine, and M. R. Wormald,
“Structure and function of x-pro dipeptide repeats in the TonB proteins of salmonella typhimurium and Escherichia coli,”Journal of Molecular Biology, vol. 216, no. 4, pp. 883–95, 1990.
[82] S. Domingo K¨ohler, A. Weber, S. P. Howard, W. Welte, and M. Dre-scher, “The proline-rich domain of TonB possesses an extended poly-proline II-like conformation of sufficient length to span the periplasm of gram-negative bacteria,”Protein Science, vol. 19, pp. 625–630, 2010.
[83] K. Postle and R. F. Good, “DNA sequence of the escherichia coli TonB gene,” Proceedings of the National Academy of Science USA, vol. 80, no. 17, pp. 5235–9, 1983.
[84] M. Meiyappan, G. Birrane, and J. A. Ladias, “Structural basis for po-lyproline recognition by the FE65 WW domain,”Journal of Molecular Biology, vol. 372, no. 4, pp. 970–80, 2007.
[85] J. Kodding, F. Killig, P. Polzer, S. P. Howard, K. Diederichs, and W. Welte, “Crystal structure of a 92-residue C-terminal fragment of TonB from escherichia coli reveals significant conformational changes compared to structures of smaller TonB fragments,” Journal of Biolo-gical Chemistry, vol. 280, no. 4, pp. 3022–8, 2005.
[86] I. Z. Steinberg, W. F. Harrington, A. Berger, M. Sela, and E. Katchal-ski, “The configurational changes of poly-l-proline in solution,”Journal of the American Chemical Society, vol. 82, no. 20, pp. 5263–5279, 1960.
[87] M. G. Gresock, M. I. Savenkova, R. A. Larsen, A. A. Ollis, and K. Post-le, “Death of the TonB shuttle hypothesis,”Frontiers in Microbiology, vol. 2, p. 206, 2011.
[88] M. Montalti and S. L. Murov,Handbook of photochemistry. Boca Ra-ton: CRC/Taylor and Francis, 3rd ed., 2006.
136 LITERATURVERZEICHNIS [89] R. S. Drago,Physical methods in chemistry. Saunders golden sunburst
series, Philadelphia: Saunders, 1977.
[90] In Zusammenarbeit mit Sebastian H¨ofel, im Rahmen seiner Masterar-beit, 2012.
[91] M. Rohrer, P. Gast, K. Mobius, and T. F. Prisner, “Anisotropic motion of semiquinones in photosynthetic reaction centers of Rhodobacter sph-aeroides R26 and in frozen isopropanol solution as measured by pulsed high-field EPR at 95 Ghz,”Chemical Physics Letters, vol. 259, no. 5-6, pp. 523–530, 1996.
[92] C. Hintze, “Elektronenspinresonanzspektroskopie an Singulett-Triplett-systemen.” Masterarbeit, 2011.
[93] G. Jeschke, A. Bender, H. Paulsen, H. Zimmermann, and A. Godt,
“Sensitivity enhancement in pulse EPR distance measurements,” Jour-nal of Magnetic Resonance, vol. 169, pp. 1–12, 2004.
[94] G. Jeschke, M. Sajid, M. Schulte, N. Ramezanian, A. Volkov, H. Zim-mermann, and A. Godt, “Flexibility of shape-persistent molecular buil-ding blocks composed of p-phenylene and ethynylene units,” Journal of the American Chemical Society, vol. 132, no. 29, pp. 10107–10117, 2010.
[95] W. D. Cornell, P. Cieplak, C. I. Bayly, I. R. Gould, K. M. Merz, D. M.
Ferguson, D. C. Spellmeyer, T. Fox, J. W. Caldwell, and P. A. Kollman,
“A 2nd generation force-field for the simulation of proteins, nucleic-acids, and organic-molecules,” Journal of the American Chemical So-ciety, vol. 117, no. 19, pp. 5179–5197, 1995.
[96] E. A. Price, B. T. Sutch, Q. Cai, P. Z. Qin, and I. S. Haworth, “Compu-tation of nitroxide-nitroxide distances in spin-labeled DNA duplexes,”
Biopolymers, vol. 87, no. 1, pp. 40–50, 2007.
[97] T. Darden, D. York, and L. Pedersen, “Particle mesh ewald - an n.log(n) method for ewald sums in large systems,”Journal of Chemical Physics, vol. 98, no. 12, pp. 10089–10092, 1993.
[98] J. P. Ryckaert, G. Ciccotti, and H. J. C. Berendsen, “Numerical-integration of cartesian equations of motion of a system with cons-traints - molecular-dynamics of n-alkanes,” Journal of Computational Physics, vol. 23, no. 3, pp. 327–341, 1977.
LITERATURVERZEICHNIS 137 [99] C. P. Poole, Electron spin resonance; a comprehensive treatise on
ex-perimental techniques. New York,: Interscience Publishers, 1967.
[100] W. Jahnke, S. Rudisser, and M. Zurini, “Spin label enhanced NMR screening,”Journal of the American Chemical Society, vol. 123, no. 13, pp. 3149–50, 2001.
Der Weg vom Anfang bis zum Abschluss dieser Arbeit war ges¨aumt von Menschen, denen ich zu großem Dank verpflichtet bin:
Dr. Malte Drescher m¨ochte an dieser Stelle zitieren:
”Promovieren ist viel mehr als das, was man in ein kleines B¨uchlein schreibt.“ Die ver-gangenen Jahre haben mich sehr gepr¨agt und viel gelehrt. Vielen Dank f¨ur das Vertrauen und die exzellente Betreuung meiner Dissertation;
Prof. Dr. Gunnar Jeschke f¨ur die wertvollen Diskussionen und die ¨ Uber-nahme des Korreferats;
Prof. Dr. Wolfram Welte und Annemarie Weber f¨ur die erfolgreiche Kooperation;
Dr. Thomas Exner und Prof. Dr. Kay Diederichs f¨ur den Beitrag zum Thema Riceverteilung in der ESR-Spektroskopie;
Prof. Dr. Ulrich Steiner f¨ur die fruchtbaren Diskussionen auf dem Ge-biet der Photochemie;
Christian Hintze und Sebastian H¨ofel, die hervorragende Masterarbei-ten zum Thema ESR-Spektroskopie an Singulett-Triplett-Systemen
Christian Hintze und Sebastian H¨ofel, die hervorragende Masterarbei-ten zum Thema ESR-Spektroskopie an Singulett-Triplett-Systemen