Ultrafast dynamics in DNA: "fraying" at the end of the helix
Ultrafast dynamics in DNA: "fraying" at the end of the helix
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DOI：
10.1021/ja0582105
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发表时间：
2006-05-31
影响因子：
15
通讯作者：
Berg, Mark A.
中科院分区：
文献类型：
--
作者：
Andreatta, Daniele;Sen, Sobhan;Berg, Mark A.
用天然碱基对被发射光谱对局部电场敏感的染料分子(香豆素102)取代的寡核苷酸，测量了DNA内部电场的动力学。通过结合时间相关光子计数、荧光上转换和瞬时吸收的结果，发射光谱的时间分辨测量已经扩展到60年的时间范围(40fs到40 ns)。最近的结果表明，当记者放置在寡核苷酸的中心时，动力学在整个时间范围内分布非常广泛，并且不显示与单个过程相关的特定时间常数(Andreatta，D.；等人)。J.Am化学。SoC。2005、127、7270)。这篇文章考察了一个寡核苷酸，记者在它的末尾。以前看到的广泛分布的松弛仍然没有什么衰减。此外，还出现了一个新的驰豫，其驰豫时间为5ps。这一过程被分配给螺旋末端的快速“磨损”部分。
The dynamics of the electric fields in the interior of DNA are measured by using oligonucleotides in which a native base pair is replaced by a dye molecule (coumarin 102) whose emission spectrum is sensitive to the local electric field. Time-resolved measurements of the emission spectrum have been extended to a six decade time range (40 fs to 40 ns) by combining results from time-correlated photon counting, fluorescence up-conversion, and transient absorption. Recent results showed that when the reporter is placed in the center of the oligonucleotide, the dynamics are very broadly distributed over this entire time range and do not show specific time constants associated with individual processes (Andreatta, D.; et al. J. Am. Chem. Soc. 2005, 127, 7270). This paper examines an oligonucleotide with the reporter near its end. The broadly distributed relaxation seen before remains with little attenuation. In addition, a new relaxation with a well-defined relaxation time of 5 ps appears. This process is assigned to the rapid component of "fraying" at the end of the helix.