Improved methods for fitting sedimentation coefficient distributions derived by time-derivative techniques
Improved methods for fitting sedimentation coefficient distributions derived by time-derivative techniques
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DOI：
10.1016/j.ab.2006.04.053
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发表时间：
2006-07-15
影响因子：
2.9
通讯作者：
Philo, John S.
中科院分区：
文献类型：
--
作者：
Philo, John S.
分析沉积速度数据的时间导数方法已经被证明是非常成功的，现在已经被常规使用了十多年。对于含有少量非相互作用物种的样品，沉降系数分布函数g(S*)传统上是用高斯函数来拟合的，以求出每个物种的浓度、沉降系数和扩散系数。然而，即使对于无噪声的数据，通过该方法获得的精度也是有限的，并且随着分析中包括更多的扫描以提高信噪比(因为数据的时间跨度变得太大)，精度甚至变得更差。描述了两种新的方法来校正长时间跨度的影响：一种方法是使用泰勒级数展开来校正理论函数，另一种方法是从边界的Lamm方程模型生成理论g(S*)曲线。使用第二种方法，拟合参数的精度约为0.1%，并且基本上与时间跨度无关，因此，在需要时可以获得更高的信噪比。第二种方法也与目前分析沉积速度数据的其他方法进行了比较。(C)2006 Elsevier Inc.保留所有权利。
Time-derivative approaches to analyzing sedimentation velocity data have proven to be highly successful and have now been used routinely for more than a decade. For samples containing a small number of noninteracting species, the sedimentation coefficient distribution function, g(s*), traditionally has been fitted by Gaussian functions to derive the concentration, sedimentation coefficient, and diffusion coefficient of each species. However, the accuracy obtained by that approach is limited, even for noise-free data, and becomes even more compromised as more scans are included in the analysis to improve the signal/noise ratio (because the time span of the data becomes too large). Two new methods are described to correct for the effects of long time spans: one approach that uses a Taylor series expansion to correct the theoretical function and a second approach that creates theoretical g(s*) curves from Lamm equation models of the boundaries. With this second approach, the accuracy of the fitted parameters is approximately 0.1% and becomes essentially independent of the time span, therefore, it is possible to obtain much higher signal/noise when needed. This second approach is also compared with other current methods of analyzing sedimentation velocity data. (c) 2006 Elsevier Inc. All rights reserved.