The determination of diffusion constants of proteins by a refractometric method.
The determination of diffusion constants of proteins by a refractometric method.
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通过折光法测定蛋白质的扩散常数。
DOI：
10.1042/bj0300528
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发表时间：
1936
期刊：
影响因子：
--
通讯作者：
Alfred Polson
中科院分区：
文献类型：
--
作者：
Ole Lamm;Alfred Polson
在根据沉降数据计算蛋白质的分子量时，必须准确了解其扩散常数。首先，通过超速离心机中沉降边界处的扩散来测量扩散常数[Svedberg，1925,1,2]，并通过测量溶液的光吸收来确定浓度变化。但在超速离心机中，不可能将温度控制到精确扩散测量所需的程度。对这种测量扩散常数的方法的另一个反对意见是，离心池中的扩散时间对于扩展系列的测量而言太短。因此，Tiselius 和 Gross [1934] 将光吸收法应用于静止管边界扩散的测量。由于照相乳剂的不规则性或溶液中的微量杂质引起的照相黑化的变化，结果持续存在小幅波动。在本文要描述的工作中，扩散装置与 Tiselius 和 Gross 使用的类似，但浓度梯度是通过我们其中一位开发的用于超速离心机的折射测量方法来测量的 [Lamm，1928； 1929]。在该方法中，通过扩散池拍摄均匀的透明标尺。扩散边界处的折射率梯度产生刻度的扭曲图像，其中当折射率是浓度的线性函数时，刻度线位移与浓度梯度成正比。装置的布置如图1所示。 ~~~~~~~~~~~~ [。
IN the calculation of the molecular weights of proteins from sedimentation data it is essential that their diffusion constants should be known accurately. At first diffusion constants were measured from the spreading at the sedimenting boundary in the ultracentrifuge [Svedberg, 1925, 1, 2] and the concentration changes were determined from measurements of the light absorption of the solutions. But in the ultracentrifuge it is impossible to control the temperature to a degree necessary for accurate diffusion measurements. A further objection to this method of measuring diffusion constants is that the time of diffusion in the centrifuge cell is far too short for an extended series of measurements. Therefore Tiselius and Gross [1934] applied the light absorption method to the measurement of duffusion at a boundary in a tube at rest. Small fluctuations in the results persisted due to variation of the photographic blackening caused by irregularities in the photographic emulsion or by traces of impurities in the solutions. In the work to be described in this paper the diffusion apparatus was similar to that used by Tiselius and Gross but the concentration gradients were measured by a refractometric method developed by one of us for use in the ultracentrifuge [Lamm, 1928; 1929]. In this method a uniform transparent scale is photographed through the diffusion cell. The refractive index gradient at the diffusion boundary produces a distorted image of the scale in which scale line displacement is proportional to the concentration gradient when the refractive index is a linear function of the concentration. The arrangement of the apparatus is shown in Fig. 1. ~~~~~~~~~~~ [.