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Biostruct Teaching: Lectures Series
Training Courses
Workshops in Transferable Skills
Expertise in Structural Biology
Atomic Force Microscopy (AFM)
Atomic Force Microscopy (AFM) allows imaging biological surfaces with sub nm resolution. Its working principle is based on the detection of repulsive forces when scanning the surface with a sharp tip. AFM based Force spectroscopy utilises its high spatial resolution, its ability to detect piconewton (1pN=10-12N) forces and its possibility to actively apply forces, for the mechanical manipulation of individual molecules. Applying forces to single molecules leads to elastic deformation and induction of structural changes. These changes reveal the molecules dynamics, conformational energies and folding pathways. Thus, force spectroscopy provides an especially valuable tool to the investigation of membrane proteins where protein structures, protein complex formation or ligand binding can be investigated.
Single molecule fluorescence spectroscopy
Single molecule fluorescence spectroscopy provides a tool for the detailed investigation of molecular structure and dynamics. The detection of Fluorescence Resonance Energy Transfer (FRET) between two fluorophores allows to measure inter- an intra-molecular distances in the nm-range with Å (1Å=10-10m) resolution. The application of this method on the single molecule level strongly increases its accuracy due to the avoidance of systematic errors. A fundamental advantage of FRET measurements is its applicability to the analysis of structures and structural changes under native conditions.
When imaging single fluorophores with a sensitive camera, in spite of the optical diffraction limit, their localisation can be determined with nanometer accuracy. This makes it possible to address individual nanoscopic particles or even single molecules with the Atomic force microscope or create fluorescence images with sub wavelength resolution.
Figure Legend:
Imaging membrane proteins (Bacteriorhodopsin) and extracting a single protein from the membrane. The forces necessary to extract an individual protein reveal the proteins structure.
