Kim W J, Ishihara T, Akaike T, Maruyama A
Department of Biomolecular Engineering, Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Japan.
Chemistry. 2001 Jan 5;7(1):176-80. doi: 10.1002/1521-3765(20010105)7:1<176::aid-chem176>3.0.co;2-m.
The accelerating effect of cationic substances on the DNA strand exchange reaction between a 20 bp DNA duplex and its complementary single strand was studied. A polycationic comb-type copolymer, that consists of a poly(L-lysine) backbone and a dextran graft chain (PLL-g-Dex) and known to stabilize triplex DNA, expedites the strand exchange reaction under physiological relevant conditions. Electrostatically a small excess of the copolymer let to a 300-1500-fold increase in the DNA strand exchange while large excess of spermine or cetyltrimethylammonium bromide, a cationic detergent known to promote markedly hybridization of complementary DNA strands, shows only a slight effect. The efficacy of the copolymer was not affected by a 10 mM Mg2+ concentration. Notably the copolymer promotes the strand exchange reaction while it stabilizes double-stranded DNA. The stabilization of strand exchange intermediates consisting of the parent duplex and the single strand by the copolymer is believed to be responsible for the observed acceleration behavior.
研究了阳离子物质对20个碱基对的DNA双链与其互补单链之间DNA链交换反应的加速作用。一种由聚（L-赖氨酸）主链和葡聚糖接枝链组成的聚阳离子梳型共聚物（PLL-g-Dex），已知其能稳定三链DNA，在生理相关条件下可加速链交换反应。从静电作用来看，少量过量的共聚物会使DNA链交换增加300至1500倍，而大量过量的精胺或十六烷基三甲基溴化铵（一种已知能显著促进互补DNA链杂交的阳离子去污剂）仅显示出轻微影响。共聚物的功效不受10 mM Mg2+浓度的影响。值得注意的是，该共聚物在稳定双链DNA的同时促进链交换反应。据信，共聚物对由亲本双链和单链组成的链交换中间体的稳定作用是观察到的加速行为的原因。
