Regensburg 2013 – scientific programme

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BP: Fachverband Biologische Physik

BP 2: Proteins

BP 2.7: Talk

Monday, March 11, 2013, 11:30–11:45, H44

Internal protein dynamics - a study on fully deuterated cyano phycocyanin by 2H NMR experiments and random-walk simulations — •Kerstin Kämpf, Beke Kremmling, and Michael Vogel — TU Darmstadt

Although possessing an ordered structure, proteins exhibit a versatile but common internal dynamics. The precise nature and geometry of this motion remains, however unclear. In order to investigate this, a combined approach of solid state 2H NMR and random-walk simulations (RWS) is used. Solid state 2H NMR is sensitive to the time scale as well as the geometry of motion[1]. It has been applied to samples of fully deuterated c-phycocyanin (hydration h= 0 g/g,h= 0.3 g/g). Suppressing the contribution of the fast methyl groups, we find that the protein backbone exhibits a temperature dependent small amplitude motion. The NMR parameters of the backbone motion are calculated by RWS for two limiting cases: A heterogeneous scenario with temperature dependent correlation times and a homogeneous scenario, in which the amplitude of motion increases with temperature. The RWS show that the existence of a T dependent amplitude of the motion is a main feature of internal protein dynamics. Nevertheless a single T dependent angle, increasing from 0°-15° for 200<T<300 K, cannot explain all experimental observations. A distribution of angles is required for a good description of the observations in 2H NMR. Thus, the present study reveals that internal protein dynamics is a complex motion with an amplitude that strongly depends on temperature.

[1]Lusceac, BBA, (2010), 1804, 41-48.