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首页> 外文期刊>Journal of Physics, D. Applied Physics: A Europhysics Journal >Dielectric relaxation in slightly hydrated bovine tendon collagen
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Dielectric relaxation in slightly hydrated bovine tendon collagen

机译：轻微水合牛腱胶原的介电弛豫

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With an aim to reveal the mechanism of water-protein interaction from the dielectric response of a model fibrous protein, the dielectric constant epsilon ' and loss factor epsilon '' have been measured in air dried and vacuum dried samples of bovine tendon collagen in the frequency range 30Hz-3MHz and temperature range 30-200 degrees C. An anomalous low frequency dispersion (LFD) and an intermediate frequency strong alpha-dispersion peak were the two main dielectric responses observed in the air dried sample. The LFD followed the fractional power law of frequency while the alpha-dispersion conformed to the Cole - Cole modified Debye equation. These dispersions, respectively, have been attributed to percolation of protons between and within the clusters of hydrogen bonded water molecules bound to polar or ionizable protein components. In the vacuum dried sample, however, a very weak high frequency alpha(2)- dispersion peak was observed, which was hidden below the strong alpha-dispersion in the air dried sample. This peak may be attributed to reorientation of polar components of the collagen molecule. Temperature dependence of the dielectric data shows release of bound water as a four-step process with discrete peaks at 50, 90, 125 and 160 degrees C. These peaks have been attributed to the onset of the release of adsorbed surface water, water bound to exposed polar sites, water bound to internal polar sites and very strongly bound structural water, respectively.
机译：为了从模型纤维蛋白的介电响应揭示水-蛋白相互作用的机理，已在风干和真空干燥的牛腱胶原样品中以如下频率测量了介电常数ε'和损耗因子ε'频率范围为30Hz-3MHz，温度范围为30-200摄氏度。异常低频分散（LFD）和中频强α分散峰是在风干样品中观察到的两个主要介电响应。 LFD遵循频率的分数幂定律，而α色散符合Cole-Cole修正的Debye方程。这些分散体分别归因于质子在与极性或可电离的蛋白质组分结合的氢键水分子簇之间和簇内的渗透。然而，在真空干燥的样品中，观察到非常弱的高频α（2）-分散峰，该峰隐藏在空气干燥样品中的强α-分散之下。该峰可归因于胶原分子的极性组分的重新取向。介电数据的温度依赖性显示出四步过程释放的结合水，在50、90、125和160摄氏度处有离散的峰值。这些峰值归因于吸附的地表水的释放，暴露的极地水，与内部极地水结合的水和非常牢固结合的结构水。

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