Barron A E, Sunada W M, Blanch H W
Department of Chemical Engineering, University of California, Berkeley, California 94720, USA.
Biotechnol Bioeng. 1996 Oct 20;52(2):259-70. doi: 10.1002/(SICI)1097-0290(19961020)52:2<259::AID-BIT7>3.0.CO;2-P.
The electrophoretic separation of DNA molecules is usually performed in thin slabs of agarose or polyacrylamide gel. However, DNA separations can be achieved more rapidly and efficiently within a microbore fused silica capillary filled with an uncrosslinked polymer solution. An early assumption was that the mechanism of DNA separation in polymer solution-capillary electrophoresis (PS-CE) is the same as that postulated to occur in slab gel electrophoresis, i.e., that entangled polymer chains form a network of "pores" through which the DNA migrates. However, we have demonstrated that large DNA restriction fragments (2.0-23.1 kbp) can be separated by CE in extremely dilute polymer solutions, which contain as little as 6 parts per million [0.0006% (w/w)] of uncrosslinked hydroxyethyl cellulose (HEC) polymers. In such extremely dilute HEC solutions, far below the measured polymer entanglement threshold concentration, pore-based models of DNA electrophoresis do not apply. We propose a transient entanglement coupling mechanism for the electrophoretic separation of DNA in uncrosslinked polymer solutions, which is based on physical polymer/DNA interactions.
DNA分子的电泳分离通常在琼脂糖或聚丙烯酰胺凝胶薄板中进行。然而，在充满未交联聚合物溶液的微内径熔融石英毛细管内，DNA分离可以更快速、高效地实现。早期的一种假设是，聚合物溶液毛细管电泳（PS-CE）中DNA分离的机制与平板凝胶电泳中假定发生的机制相同，即缠结的聚合物链形成一个“孔”网络，DNA通过该网络迁移。然而，我们已经证明，大的DNA限制性片段（2.0 - 23.1 kbp）可以在极其稀释的聚合物溶液中通过毛细管电泳进行分离，这些溶液中未交联的羟乙基纤维素（HEC）聚合物含量低至百万分之六[0.0006%（w/w）]。在如此极其稀释的HEC溶液中，远低于测得的聚合物缠结阈值浓度，基于孔的DNA电泳模型并不适用。我们提出了一种用于未交联聚合物溶液中DNA电泳分离的瞬态缠结偶联机制，该机制基于聚合物/DNA的物理相互作用。
