BETAINE CAN ELIMINATE THE BASE PAIR COMPOSITION DEPENDENCE OF DNA MELTING
BETAINE CAN ELIMINATE THE BASE PAIR COMPOSITION DEPENDENCE OF DNA MELTING
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DOI：
10.1021/bi00052a019
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发表时间：
1993-01-12
期刊：
影响因子：
2.9
通讯作者：
VONHIPPEL, PH
中科院分区：
文献类型：
--
作者：
REES, WA;YAGER, TD;VONHIPPEL, PH
我们表明，氨基酸类似物甜菜碱与小的四烷基铵离子共享[Melchior，W. B.，小的，& von HipPel，P. H.（1973）Proc.Natl. Acad. Sci. U.S.A. 70，298-302]降低或甚至消除DNA热解链转变的碱基对组成依赖性的能力。甜菜碱的“等稳定"浓度（AT和GC碱基对在此浓度下同样稳定）约为5.2 M。甜菜碱发挥其异构稳定作用，而不会明显改变双链DNA的B型构象。> 5 M甜菜碱的存在也不会极大地改变DNA作为亲核因子的行为;这种对静电相互作用的影响的缺乏是预期的，因为甜菜碱在中性pH附近作为两性亲核因子存在。在高浓度甜菜碱中DNA解链转变的研究因此允许对DNA解链的组成和亲核因子影响的实验分离。因此，甜菜碱溶液也可用于研究在等稳定化（或接近等稳定化）条件下的DNA-蛋白质相互作用，这是使用等稳定化盐不可能的。这种潜力是通过检查高度盐浓度依赖性的相互作用，核糖核酸酶A与DNA在浓缩甜菜碱溶液。
We show that the amino acid analogue betaine shares with small tetraalkylammonium ions [Melchior, W. B., Jr., & von HipPel, P. H. (I 973) Proc. Natl. Acad. Sci. U.S.A. 70, 298-302] the ability to reduce or even eliminate the base pair composition dependence of DNA thermal melting transitions. The ''isostabilizing'' concentration of betaine (at which AT and GC base pairs are equally stable) is approximately 5.2 M. Betaine exerts its isostabilizing effect without appreciably altering the conformation of double-stranded DNA from the B form. The presence of > 5 M betaine also does not greatly change the behavior of DNA as a polyelectrolyte; this lack of effect on electrostatic interactions is expected because betaine exists as a zwitterion near neutral pH. Study of DNA melting transitions in high concentrations of betaine thus allows the experimental separation of compositional and polyelectrolyte effects on DNA melting. As a consequence, betaine solutions can also be used to investigate DNA-protein interactions under isostabilizing (or close to isostabilizing) conditions, which has not been possible using isostabilizing salts. This potential is illustrated by examining the highly salt concentration-dependent interaction of ribonuclease A with DNA in concentrated betaine solutions.