Journal of Chemical Physics, Vol.107, No.14, 5621-5624, 1997
Field-cycling nuclear magnetic resonance relaxometry of molecular dynamics at biological interfaces in eye lenses: The Levy walk mechanism
We have studied the water dynamics in whole rabbit lens and fragments using H-1-field-cycling nuclear magnetic resonance relaxometry. We have measured the proton spin-lattice relaxation time T-1 as a function of the Larmor frequency, The data can be interpreted well using the reorientation mediated by translational displacement model in combination with the mechanism of bulk-mediated surface diffusion, where individual water molecules perform Levy walks with a Cauchy diffusion propagator. This gives evidence of anomalous water surface diffusion on proteins in the rabbit lens. We assume that the lens protein surface topology can be modeled by a polyhedral structure of randomly oriented faces with individual correlation lengths s(0). For the whole lens we obtained the most frequent s(0) value of 2.5 nm whereas for fragments from the rabbit cortex and the nucleus we obtained values of 3 and 0.3 nm, respectively. The correlation length values obtained for the lens can be attributed to the short-range order of the lens proteins necessary for maintaining lens transparency. (C) 1997 American Institute of Physics.