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Dr. Ralf Biehl

Neutron Spin Echo Spectroscopy (NSE) is a versatile tool to investigate large-scale movements on the 1 to 200 nanosecond timescale on different length scales with the ability to determine the relaxation time and amplitude of the motions.

In combination with other inelastic NS techniques, SANS/SAXS and NMR structure and function of proteins can be enlightened on the natural size- and time-scale of these macromolecules.

The general interest is to identify functional domain motion and characterize timescale and amplitudes by combining SANS/SAXS with NSE. In recent studies we found large-scale collective motions of domains in yeast alcohol dehydrogenase and phosphoglycerate kinase or the immunoglobulins IgG. For IgG it was possible to identify the force constant and the relevant friction contribution.

The natural environment of proteins is a crowded environment as in cells, extracellular fluids or during processing. Protein dynamics in crowded environment as a polymer mesh is considered analogous to the diffusion in a periodic potential with a fast in trap motion and a long time diffusion, which can directly measured by NSE. We examine how crowding conditions influence translational diffusion and protein internal dynamics.

Protein-Polymer conjugates - like covalent attachment of PEG e.g. via maleimide - of bioactive proteins is a widely used technique to improve delivery, biocompatibility and bioavailability of therapeutics. The influence of the attached polymer onto functional domain motion, relaxation time and amplitude is of general interest for drug design.