A5061061667- Force Microscopy Techniques and Applications
- Heat shock proteins research
- Protein Structure and Dynamics
- Molecular Junctions and Nanostructures
- Mechanical and Optical Resonators
- Polymer Surface Interaction Studies
- Enzyme Structure and Function
- ATP Synthase and ATPases Research
- Advanced Fluorescence Microscopy Techniques
- thermodynamics and calorimetric analyses
- Lipid Membrane Structure and Behavior
- Photosynthetic Processes and Mechanisms
- Osteoarthritis Treatment and Mechanisms
- Spectroscopy and Quantum Chemical Studies
- Photoreceptor and optogenetics research
- Adhesion, Friction, and Surface Interactions
- Polymer crystallization and properties
- DNA and Nucleic Acid Chemistry
- Advanced Electron Microscopy Techniques and Applications
- Integrated Circuits and Semiconductor Failure Analysis
- Computational Drug Discovery Methods
- Chemical Synthesis and Analysis
- Advanced biosensing and bioanalysis techniques
- Knee injuries and reconstruction techniques
- RNA Research and Splicing
University of Freiburg
2015-2024
Technical University of Munich
2007-2015
Nanosystems Initiative Munich
2014
University of Potsdam
2013
Center for NanoScience
2001-2012
Center for Integrated Protein Science Munich
2007-2012
Heidelberg University
2010
Chinese Academy of Sciences
2010
Schott (Germany)
2007
University of California, Berkeley
2005
Light-powered molecular machines are conjectured to be essential constituents of future nanoscale devices. As a model for such systems, we have synthesized polymer bistable photosensitive azobenzenes. Individual polymers were investigated by single-molecule force spectroscopy in combination with optical excitation total internal reflection. We able optically lengthen and contract individual switching the azo groups between their trans cis configurations. The was found against an external...
Single-molecule Förster resonance energy transfer (smFRET) is increasingly being used to determine distances, structures, and dynamics of biomolecules in vitro vivo. However, generalized protocols FRET standards ensure the reproducibility accuracy measurements efficiencies are currently lacking. Here we report results a comparative blind study which 20 labs determined (E) several dye-labeled DNA duplexes. Using unified, straightforward method, obtained with s.d. between ±0.02 ±0.05. We...
Abstract Single-molecule Förster-resonance energy transfer (smFRET) experiments allow the study of biomolecular structure and dynamics in vitro vivo. We performed an international blind involving 19 laboratories to assess uncertainty FRET for proteins with respect measured efficiency histograms, determination distances, detection quantification structural dynamics. Using two protein systems distinct conformational changes dynamics, we obtained ≤0.06, corresponding interdye distance precision...
Recent progress in atomic force microscopy (AFM) technology has allowed the measurement of inter- and intramolecular forces at level individual molecules. The mechanical manipulation single polymer chains immobilized on solid substrates become possible solution, as they are spanned stretched between tip an AFM cantilever substrate surface. This investigation far from their maximum entropy configurations stimulated refinement existing theories. From measured force-distance curves quantitative...
AFM based single molecule force spectroscopy was used for the investigation of polyelectrolyte chains. Namely, elasticity polyvinylamine chains and their desorption from solid surfaces studied as a function polymer's charge density electrolyte concentration. Experimental force−distance profiles were fitted by wormlike chain model, including elastic contributions arising stretching bond angles covalent bonds. It found that, under high forces which can be applied in experiments, bending...
Experimental single-molecule stretching curves for three backbone architectures (single-stranded DNA, various types of peptides, polyvinylamine) are quantitatively compared with corresponding quantum-chemical (zero-temperature) ab-initio calculations in the high-force range up to two nanonewtons. For high forces, quantitative agreement is obtained contour length polymers as only fitting parameter. smaller effects chain fluctuations accounted by using recent theoretical results response a...
The hydrophobic effect, i.e., the poor solvation of nonpolar parts molecules, plays a key role in protein folding and more generally for molecular self-assembly aggregation aqueous media. perturbation water structure accounts many aspects hydrophobicity. However, to what extent dispersion interaction between entities themselves contributes has remained unclear. This is so because peptide interactions structural changes occur on all length scales make disentangling various contributions...
The bacteriophage φ29 generates large forces to compact its double-stranded DNA genome into a protein capsid by means of portal motor complex. Several mechanical models for the generation these high complex predict coupling translocation rotation head-tail connector dodecamer. Putative is investigated here combining methods single-molecule force spectroscopy with polarization-sensitive fluorescence. In our experiment, we observe function in several packaging complexes parallel using video...
Significance Many proteins consist of domains that are connected by flexible linkers. Because their flexibility they usually unresolved in crystal structures. Using single-molecule force spectroscopy we were able to measure free energy changes around the thermal and obtained for first time, our knowledge, structural information on linker connecting N-domain M-domain Hsp90. We show a sequence-dependent rapid equilibrium between docked undocked state these two domains. This is facilitated...
Abstract Single-molecule FRET (smFRET) is a versatile technique to study the dynamics and function of biomolecules since it makes nanoscale movements detectable as fluorescence signals. The powerful ability infer quantitative kinetic information from smFRET data is, however, complicated by experimental limitations. Diverse analysis tools have been developed overcome these hurdles but systematic comparison lacking. Here, we report results blind benchmark assessing eleven used rate constants...
Abstract Our current understanding of biomolecular condensate formation is largely based on observing the final near-equilibrium state. Despite expectations from classical nucleation theory, pre-critical protein clusters were recently shown to form under subsaturation conditions in vitro; if similar long-lived comprising more than a few molecules are also present cells, our physical basis biological phase separation may fundamentally change. Here, we combine fluorescence microscopy with...
Abstract The molecular chaperone and heat shock protein Hsp90 is part of many complexes in eukaryotic cells. Together with its cochaperones, responsible for the maturation hundreds clients. Although having been investigated decades, it still largely unknown which components are necessary a functional complex how energy ATP hydrolysis used to enable cyclic operation. Here we use single-molecule FRET show cochaperones introduce directionality into Hsp90’s conformational changes during...
The molecular chaperone heat shock protein 90 (Hsp90) is an important and abundant in eukaryotic cells, essential for the activation of a large set signal transduction regulatory proteins. During functional cycle, Hsp90 dimer performs conformational rearrangements. transient N-terminal dimerization has been extensively investigated, under assumption that C-terminal interface stably dimerized. Using fluorescence-based single molecule assay dimers caged lipid vesicles, we were able to...
Controlling structure and function to switch ionic transport through synthetic membranes is a major challenge in the fabrication of functional nanodevices. Here we describe combination mesoporous silica thin films as structural unit, functionalized with two different redox‐responsive ferrocene‐containing polymers, polyvinylferrocene (PVFc) poly(2‐(methacryloyloxy)ethyl ferrocenecarboxylate) (PFcMA), by using either grafting to, or from approach. Both film functionalization strategies are...
Polyethylene glycol (PEG) is a structurally simple and nontoxic water-soluble polymer that widely used in medical pharmaceutical applications as molecular linker spacer. In such applications, PEG's elastic response against conformational deformations key to its function. According text-book knowledge, reacts the stretching of end-to-end separation by decrease entropy due reduction available conformations, which why polymers are commonly called entropic springs. By combination single-molecule...
The force-induced desorption of single peptide chains from mixed OH/CH3-terminated self-assembled monolayers is studied in closely matched molecular dynamics simulations and atomic force microscopy experiments with the goal to gain microscopic understanding transition between adsorption resistance as surface contact angle varied. In both experiments, surfaces become resistant against hydrophilic well hydrophobic peptides when their decreases below θ ≈ 50°–60°, thus confirming so-called Berg...
We use plasmon rulers to follow the conformational dynamics of a single protein for up 24 h at video rate. The ruler consists two gold nanospheres connected by linker. In our experiment, we molecular chaperone heat shock 90 (Hsp90), which is known show "open" and "closed" conformations. Our measurements confirm previously with transition times in second minute time scale reveals new on minutes hours. Plasmon thus extend observation bandwidth 3–4 orders magnitude respect single-molecule...
Folding of small proteins often occurs in a two-state manner and is well understood both experimentally theoretically. However, many are much larger populate misfolded states, complicating their folding process significantly. Here we study the complete assembly 1,418 amino acid, dimeric chaperone Hsp90 using single-molecule optical tweezers. Although isolated C-terminal domain shows folding, find that N-terminal as middle ensembles fast-forming, states. These intradomain misfolds slow down...
The response of switchable polymer blends and coatings to temperature variation is important for the development high-performance materials. Although this has been well studied bulk materials, a proper understanding at molecular level, in particular high stretching forces, still lacking. Here we investigate details temperature-dependent elastic two widely used water-soluble polymers, namely, polyethylene glycol (PEG) poly(N-isopropylacrylamide) (PNiPAM) with combined approach using atomic...