Physik, Chemie und Biologie mit Einzelmolekülen

Bewilligungen / Grants 2002

Single molecule dynamics in confined liquids and under shear

Bewilligung: 10.12.2002 Laufzeit: 3 Jahre

The project's aim is to relate microscopic details of the dynamics in highly confined liquid films to macroscopic processes such as friction by combining single molecule experiments with surface force measurements. The surface force apparatus is used to explore the liquid structure and solid-liquid interactions on a (sub) nanometer-scale in a liquid between atomically flat solid surfaces. The measured force is related to a layering structure observed for liquids on
solid surfaces and provides information on the solvation and the shear viscosity. However, details like anisotropies or flow gradients along
the confined region are not accessible. The proposed combination with a single molecule microscope should reveal heterogeneous diffusion of molecules, phase or stick-slip transitions and velocity distributions.

Technische Universität Chemnitz
Institut für Physik
LS Optische Spektroskopie und Molekülphysik
Dr. Frank Cichos
Postfach 122 501
09107 Chemnitz
Tel.: 0371 531 3066
Fax: 0371 531 3060
Homepage: W3:www.tu-chemnitz.de/physik/OSMP

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Mobility of single fluorescent macromolecules as a probe of the structure and dynamics of the living cell nucleus (extension)

Bewilligung: 10.12.2002 Laufzeit: 3 Jahre

The overall goal of this project is to understand the three-dimensional structure and dynamics of the chromatin fiber in the interphase nucleus, and to characterize the transport, association and dissociation of nuclear proteins that play a role in the maintenance of chromatin structure and transcription. To this aim, autofluorescent proteins are used as probes, which by way of their Brownian motion report on the structure of their immediate environment. Their motion will be studied by fluorescence correlation spectroscopy (FCS) in vivo and compared to predictions from computer simulations of the chromosome territory structure. In addition, methods will be developed to measure protein-protein interactions in vivo by two-color FCCS in a quantitative manner going beyond the level of a simple co-localization.

Deutsches Krebsforschungszentrum,
Heidelberg
Abt. Biophysik der Makromoleküle
Prof. Dr. Jörg Langowski
Im Neuenheimer Feld 280
69120 Heidelberg
Tel.: 06221 42 3390
Fax: 06221 42 3391

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Folding and assembly of single light-harvesting complexes from plants

Bewilligung: 10.12.2002 Laufzeit: 3 Jahre

In this project, individual light-harvesting chlorphyll a/b protein complexes (LHCIIb) from higher plants will be studied during their folding and assembly in vitro. The LHCIIb apoprotein binds about 15 pigments. Recombinant versions of this protein can be engineered to contain anchor groups for surface attachment, such that the immobilized protein spontaneously self-organises with pigments in solution and pigment binding and protein folding still occur simultaneously. This allows to study the complex assembly and thermal dissociation of single LCHIIb molecules by time-resolved single molecule spectroscopy. The work is expected to yield information about the inhomogeneity of folding and assembly pathways, about the sequential order of pigment binding, and the heterogeneity among individual LHCIIb molecules.

Universität Mainz
Institut für Allgemeine Botanik
Prof. Dr. Harald Paulsen
Müllerweg 6
55099 Mainz
Tel.: 06131 392 4633
Fax: 06131 392 3787
Homepage: http://iabserv.biologie.uni-mainz.de/iab/Paulsen/agpaulsen.htm

Universität Stuttgart
3. Physikalisches Institut
Dr. Carsten Tietz
Pfaffenwaldring 57
70550 Stuttgart
Tel.: 0711 685 5231
Fax: 0711 685 5281

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Cyclic metallosupramolecular dye assemblies: synthesis, characterization, and optical properties

Bewilligung: 10.12.2002 Laufzeit: 3 Jahre

Das Vorhaben wurde am 06.04.2001 bewilligt und zu dem oben angegebenen Zeitpunkt von Ulm nach Würzburg umgesetzt.

Universität Würzburg
Institut für Organische Chemie
Prof. Dr. Frank Würthner
Am Hubland
97074 Würzburg
Tel.: 0931 888 5340
Fax: 0931 888 4756

Universität Bayreuth
Lehrstuhl für Experimentalphysik IV
Prof. Dr. Jürgen Köhler
Universitätsstraße 30
95445 Bayreuth
Tel.: 0921 553240
Fax: 0921 553250

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Analysis of genome replication at the single molecule level in living cells

Bewilligung: 09.12.2002 Laufzeit: 3 Jahre

Most of our knowledge of the DNA replication and methylation machinery stems from biochemical and genetic studies. These studies suggested for example that the replication factor PCNA is rapidly turned over with a new PCNA ring loaded for every new Okazaki fragment. Our photobleaching experiments in living cells, on the other hand, indicate that there is little to no exchange of PCNA at replication foci. This project is targeted at single-molecule fluorescence microscopy for visualizing the complex process of factor association and dynamics during replication within the nuclei of living mammalian cells. The authors plan to measure the mobility and residence times of DNA replication and methylation factors in specific subnuclear domains at different cell cycle times and track their movements. A protein tranduction approach to directly deliver labeled proteins at low concentrations to living cells will be used.  

Max-Delbrück-Centrum für Molekulare
Medizin (MDC), Berlin-Buch
Franz-Volhard-Klinik
Dr. M. Cristina Cardoso

Universität München
Institut für Anthropologie und Humangenetik
Biology Department II
Prof. Dr. Heinrich Leonhardt

Universität Münster 
Institut für Medizinsche Physik und Biophysik
Prof. Dr. Ulrich Kubitscheck

Ansprechpartner:
Max-Delbrück-Centrum für Molekulare
Medizin (MDC), Berlin-Buch
Franz-Volhard-Klinik
Dr. M. Cristina Cardoso
Wiltbergstraße 50
13125 Berlin
Tel.: 030 9417 2273
Fax: 030 9417 2336

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F0F1-ATP Synthase: A rotary nano-machine

Bewilligung: 05.12.2002 Laufzeit: 3 Jahre

ATP synthase (F0 F1-ATPase) is a nano-mechanical device of biological making for electrochemical-to-mechanical (F0 portion) and mechanicalto-chemical energy transduction (F1 portion). Its normal task is to generate ATP from ADP and inorganic phosphate in order to fuel cell activity. In this project single molecule microscopy and manipulation is applied to genetically and biochemically engineered enzyme constructs which hydrolyse ATP and drive rotary motion of the central shaft of the molecule. The torque profile (under load) and the maximum rate of rotation (without load) are monitored together with binding and release of ATP and ADP. The goal is to interpret the kinetics and nano-mechanical features in terms of the atomic structure and to twin F1-motors for doubling the maximum speed of rotation or the torque.

Universität Osnabrück
Fachbereich Biologie/Chemie
Abt. Biophysik
Prof. Dr. Wolfgang Junge
Postfach 
49069  Osnabrück
Tel.: 0541 969 2872
Fax: 0541 969 2262 

Universität Osnabrück 
Fachbereich Biologie/Chemie 
Abt. Biophysik 
Dr. Oliver Pänke 
49076  Osnabrück 
Tel.: 0541 969 2873
Fax.: 0541 969 2870 

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Investigation of the electronic structure of individual photosynthetic antenna complexes -completion-
 

Bewilligung: 22.03.2002 Laufzeit: 1 Jahr

Aim of the project is a detailed study of structure-function relationships in pigment protein complexes that play a prominent role in bacterial photosynthesis. Using single molecule fluorescence spectroscopy the electronically excited states of the pigments are studied. The properties of these states depend on the geometrical arrangement of the chromophores as well as on their intermolecular coupling. For the LH2 complex from Rhodopseudomonas acidophila the team has observed new spectroscopic details which had before been concealed in ensemble averaging measurements. These experiments are extended to other lightharvesting antenna complexes: LH3 from Rhodopseudomonas acidophila and LH2 from Rhodospirillum molischianum. Hence, general implications can be assessed and peculiarities of a specific complex discriminated.

Universität Bayreuth
Lehrstuhl für Experimentalphysik IV
Prof. Dr. Jürgen Köhler
Postfach
95440 Bayreuth
Tel.: 0921 55 4000/4001
Fax: 0921 55 4002

University of Leiden
Department of Biophysics
Huygens Laboratory
Dr. Thijs J. Aartsma
Postfach POB 9504
2300 RA Leiden
NIEDERLANDE
Tel.: +31 71 52 75 700
Fax: +31 71 52 75 819

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External-field effects in single-molecule spectra: local investigation of solid-state properties at low temperatures - extension and completion -

Bewilligung: 22.03.2002 Laufzeit: 2 Jahre

In the second term of this project the investigation of spectral line shifts of single molecules caused by electric and magnetic fields as well as hydrostatic pressure is continued. The spectroscopic experiments are performed on different dye-matrix combinations with both polycrystalline and polymeric host materials. The measurements are designed to contribute to the following questions: - correlation between the line shift due to combined electric and magnetic fields, and hydrostatic pressure, - origin of the slow spectral creeping after sudden field changes, - origin of the quadratic red shift observed in magnetic fields, - shape of the absorption signal in rf modulation experiments, - reason for deviations at relatively low modulation frequencies.

Universität Bayreuth
Bayreuther Institut für Makromolekülforschung
Prof. Dr. Lothar Kador
Postfach
95440 Bayreuth
Tel.: 0921 55 3261/3241
Fax: 0921 55 3250

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Regulation of motor protein activities monitored by single molecule fluorescence microscopy in Xenopus laevis egg cell extracts

Bewilligung: 21.03.2002 Laufzeit: 3 Jahre

This project aims at measuring the single molecule behavior of microtubule dependent molecular motors under physiological conditions. This will be realized by single molecule fluorescence microscopy of motor proteins in Xenopus egg extracts. A major goal of the project is to determine how th activity of molecular motors is regulated. The results of this project will be important to understand how the activities of a variety of motor proteins contribute to organize the cytoskeleton in response to the cell's regulatory state, e.g. during cell division or during differentiation. The kinetic single molecule data will also be useful for numerical simulations that promise to explain how collective morphogenetic properties of the cytoskeleton emerge from the physical characteristics of its individual components. In more general terms, the team wants to develop a quantiative understanding of how the regulated action of molecular motors generates definded supramolecular structures composed of filaments at a nano- to microscopic scale.

EMBL - Europäisches Laboratorium
für Molekularbiologie, Heidelberg
Dr. Thomas Surrey
Meyerhofstraße 1
69117 Heidelberg
Tel.: 06221 387360
Fax: 06221 387360

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Single Molecules Synthesis

Bewilligung: 21.03.2002 Laufzeit: 3 Jahre

The project`s aim is to perform chemical synthesis at the molecular level exploiting the capability of low temperature scanning tunneling microscopy (STM). Three key steps in single molecule synthesis are investigated. First, the preparation of the reactands in the right orientation and conformation on metal as well as insulating surfaces with the help of the STM tip must be achieved. Then, the activation to perform the reaction is examined using again the STM. Finally, the reaction and intermediate products are identified by vibrational spectroscopy and manipulation. The developed method can then be applied to build complex and precisely designed molecular devices. The groups in Toulouse work on the synthesis of suitable reactand molecules and on theoretical calculations. The STM experiments take place in Berlin.

CNRS - CEMES Centre d'Elaboration de
Materiaux et d'Etudes Structurales,
Toulouse
Molecular Electronics Group
Dr. André Gourdon

CNRS - CEMES Centre d'Elaboration de
Materiaux et d'Etudes Structurales,
Toulouse
Molecular Electronics Group
UP 8011, BP 4347
Dr. Christian Joachim

Freie Universität Berlin
Institut für Experimentalphysik
Dr. Francesca Moresco

Ansprechpartner:
CNRS - CEMES Centre d'Elaboration de
Materiaux et d'Etudes Structurales,
Toulouse
Molecular Electronics Group
Dr. André Gourdon
29, rue Jeanne-Marvig
F-31055 Toulouse CEDEX 04
FRANKREICH
Tel.: +33 5 62 25 78 59
Fax: +33 5 62 25 79 99

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Spring School on Physics, Chemistry and Biology with Single Molecules

08.04.2002 - 12.04.2002 in Hofgeismar

Universität Bremen
Institut für Experimentelle Physik
Prof. Dr. Ulrich Kubitscheck

Universität Münster
Physikalisches Institut
Dr. Ulrich Fischer

Universität Münster
Physikalisches Institut
Dr. Andreas Naber

Ansprechpartner:
Universität Bremen
Institut für Experimentelle Physik
Prof. Dr. Ulrich Kubitscheck
Postfach 330 440
28334 Bremen
Tel.: 0421 218 2448
Fax: 0421 218 2974

 

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