Stellwagen N C, Gelfi C, Righetti P G
Department of Biochemistry, University of Iowa, Iowa City 52242, USA.
Biopolymers. 1997 Nov;42(6):687-703. doi: 10.1002/(SICI)1097-0282(199711)42:6<687::AID-BIP7>3.0.CO;2-Q.
The free solution mobility of DNA has been measured by capillary electrophoresis in the two buffers most commonly used for DNA gel electrophoresis, Tris-borate-EDTA (TBE) and Tris-acetate-EDTA (TAE). The capillaries were coated with polymers of either of two novel acrylamide monomers, N-acryloylaminoethoxyethanol or N-acryloylaminopropanol, both of which are stable at basic pH and effectively eliminate the electroendosmotic mobility due to the capillary walls. The free solution mobility of DNA in TAE buffer was found to be (3.75 +/- 0.04) x 10(-4) cm2 V-1 s-1 at 25 degrees C, independent of DNA concentration, sample size, electric field strength, and capillary coating, and in good agreement with other values in the literature. The free solution mobility was independent of DNA molecular weight from approximately 400 base pairs to 48.5 kilobase pairs, but decreased monotonically with decreasing molecular weight for smaller fragments. Surprisingly, the free solution mobility of DNA in TBE buffer was found to be (4.5 +/- 0.1) x 10(-4) cm2 V-1 s-1, about 20% larger than observed in TAE buffer, presumably because of the formation of nonspecific borate-deoxyribose complexes.
已通过毛细管电泳法在两种最常用于DNA凝胶电泳的缓冲液（Tris-硼酸-EDTA（TBE）和Tris-乙酸-EDTA（TAE））中测量了DNA的自由溶液迁移率。毛细管涂覆有两种新型丙烯酰胺单体之一的聚合物，即N-丙烯酰基氨基乙氧基乙醇或N-丙烯酰基氨基丙醇，这两种单体在碱性pH下均稳定，并能有效消除由于毛细管壁引起的电渗迁移率。发现在25℃下，DNA在TAE缓冲液中的自由溶液迁移率为(3.75±0.04)×10⁻⁴ cm² V⁻¹ s⁻¹，与DNA浓度、样品大小、电场强度和毛细管涂层无关，并且与文献中的其他值吻合良好。自由溶液迁移率在大约400个碱基对至48.5千碱基对的DNA分子量范围内是独立的，但对于较小片段，随着分子量的降低而单调下降。令人惊讶的是，发现DNA在TBE缓冲液中的自由溶液迁移率为(4.5±0.1)×10⁻⁴ cm² V⁻¹ s⁻¹，比在TAE缓冲液中观察到的大约大20%，大概是由于形成了非特异性硼酸-脱氧核糖复合物。
