Trifonov A, Raytchev M, Buchvarov I, Rist M, Barbaric J, Wagenknecht H-A, Fiebig T
Eugene F. Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467, USA.
J Phys Chem B. 2005 Oct 20;109(41):19490-5. doi: 10.1021/jp052108c.
Ultrafast structural dynamics concomitant to excitation energy transfer in DNA has been studied using a pair of pyrene-labeled DNA bases. The temporal evolution of the femtosecond pump-probe spectra reveals the existence of two electronic coupling pathways, through-base stack and through-space, which lead to excitation energy transfer and excimer formation even when the labeled DNA bases are separated by one AT base pair. The electronic coupling which mediates through-base stack energy transfer is so strong that a new absorption band arises in the excited-state absorption spectrum within 300 fs. From the analysis of time-dependent spectral shifts due to through-space excimer formation, the local structural dynamics and flexibility of DNA are characterized on the picosecond and nanosecond time scale.
利用一对芘标记的DNA碱基，研究了与DNA中激发能转移相伴的超快结构动力学。飞秒泵浦-探测光谱的时间演化揭示了存在两条电子耦合途径，即通过碱基堆积和通过空间，即使标记的DNA碱基被一个AT碱基对隔开，这两条途径也会导致激发能转移和准分子形成。介导通过碱基堆积的能量转移的电子耦合非常强，以至于在300飞秒内激发态吸收光谱中出现了一个新的吸收带。通过对由于通过空间形成准分子而导致的时间相关光谱位移的分析，在皮秒和纳秒时间尺度上表征了DNA的局部结构动力学和柔韧性。
