Studies of DNA dumbbells. IV. Preparation and melting of a DNA dumbbell with the 16 base-pair sequence 5'G-T-A-T-C-C-C-T-C-T-G-G-A-T-A-C3' linked on the ends by dodecyl chains.
Studies of DNA dumbbells. IV. Preparation and melting of a DNA dumbbell with the 16 base-pair sequence 5'G-T-A-T-C-C-C-T-C-T-G-G-A-T-A-C3' linked on the ends by dodecyl chains.
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DNA哑铃的研究。
DOI：
10.1002/bip.360331203
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发表时间：
1993
期刊：
影响因子：
2.9
通讯作者：
Benight,AS
中科院分区：
文献类型：
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作者：
Doktycz,MJ;Paner,TM;Benight,AS
描述了通过C12 H24（十二烷基）链在两端连接的16个碱基对双链体DNA的制备和解链。测量十二烷基连接的分子和在末端连接而不是通过T4环连接的相同双链体分子的吸光度与温度曲线（光学熔解曲线）。在25、55和85 mMNa+中测量了两种分子的光学熔解曲线，结果显示，无论[Na+]如何，由十二烷基环连接的双链体比由T4环连接的相同双链体稳定至少6°C。根据双态和多态理论模型分析了每种盐环境中的实验曲线。在两态或范特霍夫分析中，熔化转变被假设为以全或无的方式发生。因此，在整个解链转变过程中，分子唯一可能进入的状态是完全完整的双链体和完全解链的双链体或小环。在多态分析中，不需要关于熔融转变的假设，并且明确考虑了双链体的每种可能的部分熔融状态的统计发生。分析结果显示，十二烷基连接分子和具有T4末端环的哑铃状分子的熔融转变基本上是25和55 mMNa+中的两种状态。相比之下，在85 mMNa+中观察到与双态行为的显著偏离。根据我们先前发表的具有Tnend环的DNA哑铃的解链数据，其中n = 2，3，4，6，8，10，14 [T. M. Paner，M. Amaratunga和A. S. Benight，（1992）Biopolymers，第32卷，第32页。881-892]和本研究的具有T4末端环的哑铃形，构建d（Tm）/dln [Na+]图。该数据ton= 1的外推与烷基连接哑铃型分子获得的d（Tm）/dln [Na+]值相交，表明烷基连接分子的盐依赖性稳定性表现为该分子的双链体通过由单个T残基组成的末端环连接。John Wiley & Sons，Inc.
The preparation and melting of a 16 base‐pair duplex DNA linked on both ends by C12H24(dodecyl) chains is described. Absorbance vs temperature curves (optical melting curves) were measured for the dodecyl‐linked molecule and the same duplex molecule linked on the ends instead by T4loops. Optical melting curves of both molecules were measured in 25, 55, and 85 mMNa+and revealed, regardless of [Na+], the duplex linked by dodecyl loops is more stable by at least 6°C than the same duplex linked by T4loops. Experimental curves in each salt environment were analyzed in terms of the two‐state and multistate theoretical models. In the two‐state, or van't Hoff analysis, the melting transition is assumed to occur in an all‐or‐none manner. Thus, the only possible states accessible to the molecule throughout the melting transition are the completely intact duplex and the completely melted duplex or minicircle. In the multistate analysis no assumptions regarding the melting transition are required and the statistical occurrence of every possible partially melted state of the duplex is explicitly considered. Results of the analysis revealed the melting transitions of both the dodecyl‐linked molecule and the dumbbell with T4end loops are essentially two state in 25 and 55 mMNa+. In contrast, significant deviations from two‐state behavior were observed in 85 mMNa+. From our previously published melting data of DNA dumbbells with Tnend loops wheren= 2, 3, 4, 6, 8, 10, 14 [T. M. Paner, M. Amaratunga, and A. S. Benight, (1992)Biopolymers, Vol. 32, pp. 881–892] and the dumbbell with T4end loops of this study, a plot ofd(Tm)/dln [Na+] was constructed. Extrapolation of this data ton= 1 intersects with the value ofd(Tm)/dln [Na+] obtained for the alkyl‐linked dumbbell, suggesting the salt‐dependent stability of the alkyl‐linked molecule behaves as though the duplex of this molecule were linked by end loops comprised of a single T residue. © 1993 John Wiley & Sons, Inc.