NMR and dielectric studies of hydrated collagen and elastin: Evidence for a delocalized secondary relaxation

Abstract

Using a combination of dielectric spectroscopy and solid-state deuteron NMR, the hydration water dynamics of connective tissue proteins is studied at sub-ambient temperatures. In this range, the water dynamics follows an Arrhenius law. A scaling analysis of dielectric losses, 'two-phase' NMR spectra, and spin-lattice relaxation times consistently yield evidence for a Gaussian distribution of energy barriers. With the dielectric data as input, random-walk simulations of a large-angle, water reorientation provide an approximate description of stimulated-echo data on hydrated elastin. This secondary process is quasi-isotropic and delocalized. The delocalization is inferred from previous NMR diffusometry experiments. It is emphasized that the phenomenology of this process is shared by many non-aqueous binary glasses in which the constituent components exhibit a sufficient dynamical contrast.

NMR and conductivity studies of the mixed glass former effect in lithium borophosphate glasses

“…6 for x = 0.5, distributions of activation energies, g( E), can be evaluated from detailed line shape analyses. Furthermore, g( E) is accessible from an appropriate scaling of spin-lattice relaxation times T 1 as follows: 55 We start from a superposition of spectral densities, yielding the relaxation rate, cf. Eq.…”

Static and pulsed field gradient nuclear magnetic resonance studies of water diffusion in protein matrices

“…In particular, it was argued that protein dynamics are slaved 2 or plasticized 3 by water dynamics. To shed light on this dynamical interplay, a number of experimental [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] and computational [22][23][24][25][26][27][28] works studied rotational and translational motions of nonfreezable water in the hydration shells of proteins. Despite significant improvement of our knowledge in the last decade, there is still a controversial debate whether dynamics of protein hydration waters can be regarded as a a) Electronic mail: michael.vogel@physik.tu-darmstadt.de.…”

“…4 Interestingly, an improved data analysis did not yield a FS transition. In studies on the rotational motion of protein hydration waters, the existence of a FS transition was ruled out, [9][10][11][12][13][14][15][16][17][18][19][20] which does not exclude that for some reason, the nature of water dynamics changes upon cooling, including a mild crossover in temperature-dependent correlation times.…”

Hierarchical viscosity of aqueous solution of tilapia scale collagen investigated via dielectric spectroscopy between 500 MHz and 2.5 THz

“…Most of the water remains as free water in the networks, even in the 4 wt% aqueous solution of collagen. This is not an unreasonable idea because a dielectric study of glassy hydrated collagen (~80 wt%) suggested that water has significant mobility even in a rigid collagen matrix below the denaturation temperature21. It is worth noting that the network for the aqueous solution of 4 wt% collagen molecules involves almost 2000 collagen rods in a cube with sides the length of the collagen (300 nm).…”