Martenson R E
J Biol Chem. 1978 Dec 25;253(24):8887-93.
The hydrodynamic behavior of bovine myelin basic protein was studied by gel filtration through Sephadex G-100 under conditions which included variations in pH from 2 to 12, variations in ionic strength from 0.01 to 1.5 M at pH 2 and from 0.1 to 2 M at pH 7, and variations in guanidinium chloride concentration from 0 to 6 M. A number of well characterized compact globular proteins were subjected to the same conditions for comparison. Compact globular proteins showed major conformational transitions due to acid, alkali, and guanidinium chloride denaturation and, possibly, minor transitions as well. Myelin basic protein behaved like a flexible linear polyelectrolyte, expanding continuously between pH 11 and pH 2 to 3 at ionic strength 0.1 M and contracting continuously with increase in ionic strength at pH 2 and at pH 7 to the point of salting-out. Relatively low concentrations of guanidinium chloride (approximately 0.5 M) were sufficient to cause the basic protein to expand. With increasing concentration of the denaturant the molecule continued to expand, but in a noncooperative manner. These results demonstrated the lack of significant intramolecular stabilization in the protein.
在多种条件下通过Sephadex G - 100凝胶过滤研究了牛髓鞘碱性蛋白的流体动力学行为。这些条件包括pH值在2至12之间变化、离子强度在pH 2时从0.01到1.5 M以及pH 7时从0.1到2 M变化，还有氯化胍浓度从0到6 M变化。一些特征明确的紧密球状蛋白也在相同条件下进行比较。紧密球状蛋白由于酸、碱和氯化胍变性会发生主要的构象转变，可能还会有次要转变。髓鞘碱性蛋白表现得像一种柔性线性聚电解质，在离子强度为0.1 M时，在pH 11至pH 2到3之间持续膨胀，在pH 2和pH 7时随着离子强度增加而持续收缩直至盐析点。相对低浓度的氯化胍（约0.5 M）就足以使碱性蛋白膨胀。随着变性剂浓度增加，分子继续膨胀，但以非协同方式。这些结果表明该蛋白缺乏显著的分子内稳定性。
