Ralston G B, Teller D C, Bukowski T
Department of Biochemistry, University of Sydney, Australia.
Anal Biochem. 1989 Apr;178(1):198-201. doi: 10.1016/0003-2697(89)90379-5.
In meniscus depletion sedimentation equilibrium experiments, the solute concentration gradient in much of the cell is insufficient to stabilize against thermal convection. Experiments with spectrin at 35 degrees C led to sufficient convection that, particularly at low concentrations of solute, no apparent redistribution occurred. At low angular velocity, the density gradient provided by moderate concentrations of NaCl or additional sucrose is inadequate to overcome the convective disturbances. We have found that the use of low concentrations of metrizamide can overcome these problems. The higher molecular weight and lower partial specific volume of metrizamide vis-a-vis sucrose allow a significant and stabilizing density gradient even at angular velocities below 8000 rpm.
在半月板耗尽沉降平衡实验中，细胞大部分区域的溶质浓度梯度不足以抵抗热对流而保持稳定。在35摄氏度下用血影蛋白进行的实验导致了足够的对流，特别是在低溶质浓度时，没有明显的重新分布发生。在低角速度下，中等浓度的氯化钠或额外的蔗糖提供的密度梯度不足以克服对流干扰。我们发现，使用低浓度的甲泛葡胺可以克服这些问题。相对于蔗糖，甲泛葡胺具有更高的分子量和更低的比容，即使在角速度低于8000转/分钟时也能形成显著且稳定的密度梯度。
