Proteins
Biological membranes consist of a double layer (phospholipids) that separates cells or creates intracellular compartments controlling what substances enter and leave. Membranes and proteins within them play an important function in trafficking and transport and are involved in health and diseases. Membrane less organelles lack these membranes but still have important cellular functions.
Proteins are the molecular machinery of life. As nanomachines of metabolism, they are in every cell of our body tirelessly active, transport, synthesize, divide and transform substances. The ability of specific proteins to do their job is determined by the sequence of amino acids and their three-dimensional arrangement, but also depends on structural rearrangements dependent on the environmental conditions. Yet, a large class of proteins is characterized by intrinsic disorder thus exhibiting conformational properties known for polymers.
Neutron scattering methods allow examination of structure and dynamics of biological structures. Biological samples can be examined in D2O buffer solution close to the natural state in the cell without radiation damage. Small Angle Scattering (SAXS/SANS) allows determination of biomolecular structures in solution. 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 [1]. Quasi-elastic scattering methods as time of flight (TOF) or backscattering (BS) allow the examination on subnanosecond timescale to access motions of amino acid sidechains or hydrogens. Neutron protein crystallography opens up the possibility to locate hydrogen atoms even at moderate resolutions of 2 Å.
References:
- R. Biehl, M. Monkenbusch, and D. Richter, Soft Matter 7, 1299 (2011)
Exploring internal protein dynamics by neutron spin echo spectroscopy
Soft Matter 7, 1299 (2011).
Topics:
Biological Membranes
Liquid-Liquid Phase Separation in biological materials
Intrinsically disordered proteins (IDP) and unfolded proteins
Functional collective dynamics of domains
Protonation states of proteins