Investigation of the dynamical properties of water in elastin by deuterium Double Quantum Filtered NMR

Abstract

The anisotropic motion of tightly bound waters of hydration in bovine nuchal ligament elastin has been studied by deuterium Double Quantum Filtered (DQF) NMR. The experiments have allowed for a direct measurement of the degree of anisotropy within pores of elastin over a time scale ranging from 100 μs to 30 ms, corresponding to a tortuous spatial displacement ranging from 0.2 to 7 μm. We studied the anisotropic motion of deuterium nuclei in D2O hydrated elastin over a temperature of −15 °C to 37 °C and in solvents with varying dielectric constants. Our experimental measurements of the residual quadrupolar interaction as a function of temperature are correlated to the existing notion of hydrophobic collapse near 20 °C.

Effects of solvent concentration and composition on protein dynamics: 13 C MAS NMR studies of elastin in glycerol–water mixtures

“…There, changes of backbone dynamics under mechanical deformation were reported to be linked to changes of water dynamics [57]. In addition, variations of the elastin structure with increasing temperature or strain were found to be accompanied by an ordering of the hydration water [58,59].…”

Double and zero quantum filtered 2H NMR analysis of D2O in intervertebral disc tissue

“…Although the use of 2 H DQF NMR is an in vitro technique, it provides more useful information than 1 H DQF NMR [16]. 2 H DQF NMR spectroscopy has been applied to a range of hydrated materials, demonstrating that by measuring the fundamental NMR parameters connection between the NMR spectroscopy and molecular level models of hydration can be made [20][21][22][23]. The NMR signal in the 2 H DQF experiment is created by water molecules that do not undergo complete isotropic motion due to interactions with a solid matrix, leading to an incomplete averaging of their quadrupolar interaction.…”

Applications of solid state NMR to cardiolipin and elastin.

“…MQ spectroscopy is useful in this case because it allows one to distinguish ordered, anisotropically reorienting water, from the bulk, isotropic water. MQ NMR has been used for solvent ordering measurements in a variety of systems, including purple membrane suspensions [99], polymer membranes like Nafion [100], biological samples such as blood vessels [105], cartilage [104], spinal disk tissue [108][109], collagen [103,[110][111], and elastin [112][113]. We have improved on the pulse sequence commonly used, and devised a method for analysis of the results that allows us to estimate the amount of ordered water in the sample and the strength of the residual quadrupolar coupling, i.e., the degree to which the water is ordered at the protein surface.…”

“…A recent study of elastin [112][113] by 2Q NMR reports dispersion signal which hampers quantitative analysis. The pulse sequence designed here successfully circumvents these problems due to addition of alignment and purging and allows observation of an absorption mode signals.…”

“…Transient interaction of solvent at the surface and diffusional exchange with surrounding solvent are inherent features of the hydrophobic effect [132] and a unique advantage of NMR compared to other experimental methods in this context is that time-dependent processes can be studied while the system is at equilibrium. Second, magnetic resonance imaging (MRI) based on MQ NMR is an emerging technique [97,104,[110][111][112] and the underlying physical chemistry of how water interacts with a soft tissue and can be used to efficiently generate MQ coherence is fundamental to obtaining image contrast.…”