Serwer P, Harris R A, Miller M M, Griess G A
Department of Biochemistry, University of Texas Health Science Center, San Antonio 78284-7760, USA.
Electrophoresis. 1996 Jun;17(6):971-6. doi: 10.1002/elps.1150170603.
When testing theoretical models that quantitatively describe the sieving of macromolecules during gel electrophoresis, investigators have been limited by absence of control of the heterogeneity of the size of pores in the gel. In a recent study performed by electron microscopy of thin sections (G. A. Griess et al., J. Struct. Biol. 1993, III, 39-47), pore size heterogeneity has been increased for agarose gels by a combination of both derivatization and molecular weight reduction of the polysaccharide chains of agarose. In the present study, pore size heterogeneity is increased by a mechanism that appears to have an origin different from the origin of this previously observed increase in heterogeneity: Pore size heterogeneity is increased by addition of a polyethylene glycol (PEG) of high molecular weight (18,500) to molten agarose before gelation. In contrast, the use of a lower molecular weight PEG (either 4,000 or 7,500) causes the formation of micron-sized precipitates within a gelled network of agarose fibers. Thus far, the PEG-induced heterogeneity of pore size occurs primarily in 100-1,000 microns scale zones separated from each other by interzone regions of decreased agarose fiber density. More uniform gels are needed for the study of sieving.
在测试定量描述大分子在凝胶电泳过程中筛分情况的理论模型时，研究人员一直受到凝胶中孔隙大小异质性缺乏控制的限制。在最近一项通过薄切片电子显微镜进行的研究（G. A. 格里斯等人，《结构生物学杂志》，1993年，第III卷，第39 - 47页）中，通过琼脂糖多糖链的衍生化和分子量降低相结合的方法，增加了琼脂糖凝胶的孔隙大小异质性。在本研究中，孔隙大小异质性通过一种似乎与先前观察到的异质性增加来源不同的机制增加：在凝胶化前向熔融琼脂糖中添加高分子量（18,500）的聚乙二醇（PEG）来增加孔隙大小异质性。相比之下，使用较低分子量的PEG（4,000或7,500）会在琼脂糖纤维的凝胶网络内形成微米级沉淀。到目前为止，PEG诱导的孔隙大小异质性主要发生在100 - 1,000微米尺度的区域，这些区域被琼脂糖纤维密度降低的区域相互隔开。筛分研究需要更均匀的凝胶。
