Regensburg 2010 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 12: Soft Matter I

DY 12.1: Talk

Tuesday, March 23, 2010, 14:30–14:45, H47

²H NMR study on the molecular motion of water in hydrated myoglobin — •Sorin Adrian Lusceac and Michael Vogel — Institut für Festkörperphysik, Technische Universität Darmstadt, Hochschulstr. 6, 64289 Darmstadt

The physiological properties of proteins are strongly dependent on the water dynamics (WD) in their hydration shell. Hence, ²H NMR spin-lattice relaxation and solid-echo experiments were performed to investigate the WD in a water/myoglobin mixture. The obtained rotational correlation times agree with those from dielectric spectroscopy measurements. They can be described by an Arrhenius law in the high temperature range, with the possibility of a weak crossover to a second Arrhenius dependence at about 220K. No evidence for a fragile-to-strong transition, as proposed in literature[1], is found, consistent with results for hydrated elastin and collagen[2,3]. From the spectral analysis, we conclude that at high temperatures (>230K) the WD is isotropic while at lower temperatures (<220K) anisotropic large-angle dynamics is observed. We performed random-walk simulations for several anisotropic WD models and discuss the resulting spectra in connection with the experimental results.

[1] S.-H. Chen et al., Proc. Natl. Acad. Sci. 103 (2006) 9012.

[2] M. Vogel, Phys. Rev. Lett. 101 (2008) 225701.

[3] S. A. Lusceac et al., Biochim. Biophys. Acta 1804 (2010) 41.