Rowe E S, Steinhardt J
Biochemistry. 1976 Jun 15;15(12):2579-85. doi: 10.1021/bi00657a015.
Two independent electrooptical properties, the specific Kerr constants and the electric birefringence relaxation times, of the saturated sodium dodecyl sulfate complexes of a series of reduced polypeptides of known molecular weight are reported. Both the Kerr constants and the relaxation times are unique functions of the molecular weight of the polypeptide chain. The specific Kerr constants depend upon the square of the polypeptide molecular weight. The relaxation times of the complexes, which are proportional to the rotational diffusion constants, are dependent on the molecular weight to approximately the first power. The latter finding is inconsistent with the compact prolate ellipsoid model for sodium dodecyl sulfate-protein complexes proposed by Reynolds and Tanford ((1970) J. Biol. Chem. 245, 5161) in which the cross section is constant and the length depends on linearly on molecular weight; for this model the relaxation times would depend on approximately the 2.5 power of the molecular weight in the range of sizes investigated. Combination of the present results with other properties in the literature rules out a number of other models characterized by compactness and near inflexibility. No firm conclusions can be drawn as to the suitability of the free-draining flexible model of Shirahama, Tsujii, and Takagi ((1974) J. Biochem. (Tokyo) 75, 309).
报道了一系列已知分子量的还原多肽的饱和十二烷基硫酸钠复合物的两种独立电光性质，即比克尔常数和电双折射弛豫时间。克尔常数和弛豫时间都是多肽链分子量的独特函数。比克尔常数取决于多肽分子量的平方。复合物的弛豫时间与旋转扩散常数成正比，大约与分子量的一次方有关。后一发现与雷诺兹和坦福德（(1970)《生物化学杂志》245, 5161）提出的十二烷基硫酸钠 - 蛋白质复合物的紧密长椭球体模型不一致，在该模型中横截面是恒定的，长度与分子量呈线性关系；对于该模型，弛豫时间在研究的尺寸范围内将大约取决于分子量的2.5次方。将目前的结果与文献中的其他性质相结合，排除了许多其他以紧密性和近乎刚性为特征的模型。对于白滨、辻井和高木（(1974)《生物化学杂志》（东京）75, 309）提出的自由排水柔性模型的适用性，无法得出确凿结论。
