Bodurka, J. ; Buntkowsky, G. ; Gutsze, A. ; Masierak, W. (1999)
NMR study of role of the cross-relaxation effect in the cortex and the nucleus rabbit lens fragments.
In: Colloids and Surfaces a-Physicochemical and Engineering Aspects, 158 (1-2)
Artikel, Bibliographie

Kurzbeschreibung (Abstract)

We have experimentally studied the coupling between the longitudinal magnetization of macromolecular protons and water protons in the cortex and the nucleus rabbit lens fragments (cross-relaxation). The NMR lines of water protons in the cortex and the nucleus of rabbit lens are inhomogenously broadened and relative narrow. We have assumed that the NMR line of crystalline protons in the lens is homogeneously broadened, very broad (the halfwidth order of 25 kHz) with small intensity. To detect the effect of cross-relaxation we adopted concept of the magnetization transfer used in magnetic resonance imaging. We irradiated the sample 20 kHz off resonance of the water protons with a train of low power RF pulses forming a selective saturation pulse and then after variable delay excited with a high-power 90 degrees, detection pulse. Finally we have measured the sample NMR line intensity as a function of duration of selective pulse for several fixed delays between selective and detection pulses. We have found the significant difference between time constants of decays for the cortex and the nucleus. We attributed this difference to longer time of hydration water molecules in the cortex spend within proximity of the protein surface than in the nucleus. We have interpreted these finding as an effect of chemical protons exchange between macromolecular and water protons rather then cross-relaxation effects, and it is discussed in terms of the Levy walk mechanism. (C) 1999 Elsevier Science B.V. All rights reserved.

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