Regensburg 2013 – scientific programme
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BP: Fachverband Biologische Physik
BP 2: Proteins
BP 2.3: Talk
Monday, March 11, 2013, 10:15–10:30, H44
Structure and dynamics of the iron binding protein Lactoferrin studied with neutron scattering — •Clemens Sill1, Ralf Biehl1, Bernd Hoffmann2, and Dieter Richter1 — 1JCNS-1 & ICS-1: Neutron Scattering, Forschungszentrum Jülich, Germany — 2ICS-7: Biomechanics, Forschungszentrum Jülich, Germany
The understanding of the functionality of proteins started with a rigid model, namely the Lock and Key analogy. Meanwhile, a more dynamic and flexible picture of these macromolecules has evolved to explain protein function. The importance of thermodynamically driven, internal motions for the functioning of proteins is subject of ongoing research.
Lactoferrin is an iron-binding protein with antimicrobial activity as a part of the innate immune system. It consists of two binding sites located in a cleft of the two main domains, each is capable of binding and releasing one iron ion. A combined approach of Small Angle Neutron Scattering for structural characterization and Neutron Spin Echo spectroscopy to elucidate the dynamic properties of different binding states was undertaken to enlighten the influence of iron binding on large scale protein dynamics. A comparison of the SANS data with 3D structures (crystallography and homology models) proved that the binding sites are closed when occupied by iron and open otherwise. In combination with normal mode analysis it was found from the NSE measurements that the internal dynamics are dominated by fluctuations of the main domains relative to each other. Stretching and twisting motions can describe the found dynamics, and their occurrence is independent whether the domains are open or closed.