Biomolecules and nano-assemblies

Knowledge of the structure and dynamics of biomolecules is of upmost importance for understanding of their function. This research area deals with the development of techniques to determine the structure of large biomolecular complexes or other nano-assemblies by ultrabright, short-pulse x-rays or electrons. We want to create the experimental basis for the future use of the table-top x-ray free-electron laser, TT-XFEL, being developed in Garching. The aim is to overcome the current limitation of structure determination imposed by the availability of large crystals. Starting with small crystals and single-shot experiments, we shall work with microcystals of decreasing size down to single molecules. Soft x-ray free-electron lasers (e. g. VUV DESY) will be used to study the sample Coulomb explosion at high intensities and the conformation of proteins in the gas phase. Coherent imaging experiments will be performed with synchrotron radiation and with VUV-FEL radiation. Techniques will be developed to align microcrystals with ultrafocused beams and to correlate diffraction patterns from many multiple, arbitrarily-oriented specimens. For biologically relevant applications, we will develop methods of generating ordered biological nano-assemblies by using natural frameworks such as two-dimensional membrane-bound proteins. Systematic investigation of radiation damage and its recovery is performed by irradiation of proteins with pulses of electron beams together with analysis by advanced infrared spectroscopy. A broadband infrared spectroscopic near-field microscope is to be developed which allows spectroscopic investigations at high spatial resolution.