UV RESONANCE RAMAN STUDIES OF DNA PYRENE INTERACTIONS - OPTICAL DECOUPLING RAMAN-SPECTROSCOPY SELECTIVELY EXAMINES EXTERNAL SITE BOUND PYRENE
UV RESONANCE RAMAN STUDIES OF DNA PYRENE INTERACTIONS - OPTICAL DECOUPLING RAMAN-SPECTROSCOPY SELECTIVELY EXAMINES EXTERNAL SITE BOUND PYRENE
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DOI：
10.1021/ja00067a059
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发表时间：
1993-07-14
影响因子：
15
通讯作者：
ASHER, SA
中科院分区：
文献类型：
--
作者：
CHO, N;ASHER, SA
芘插入 DNA 会导致那些与核酸电子跃迁重叠的芘电子吸收带出现强烈的减色现象。在这些吸收带内激发的芘的共振拉曼截面减少了 10-100 倍。拉曼饱和度测量表明插层芘非辐射弛豫率显着增加，这与荧光猝灭观察结果一致。我们使用光学解耦拉曼光谱（ODRS）新技术证明，剩余的荧光来自未插入碱基之间的芘，但很可能在外部结合。 ODRS 涉及双脉冲序列，其中泵浦激光器在光谱区域激发样品，该光谱区域被一种成分选择性吸收；泵选择性地将该组件激发出其电子基态。探针脉冲监测样品中剩余基态物质的拉曼光谱，在这种情况下选择性地富集插层芘。插层芘的拉曼强度和增强模式与外部位点结合芘有很大不同。 ODRS 的这项新技术使我们能够选择性地监测结合在 DNA 两个不同位点的芘分子，是研究复杂系统的一种新的通用方法。
Intercalation of pyrene into DNA results in a strong hypochromism of those pyrene electronic absorption bands which overlap the nucleic acid electronic transitions. The resonance Raman cross sections of pyrene excited within these absorption bands are decreased by factors of 10-100-fold. Raman saturation measurements indicate a dramatic increase in the intercalated pyrene nonradiative relaxation rate, which is consistent with fluorescence quenching observations. We demonstrate using the new technique of optical decoupling Raman spectroscopy (ODRS) that the remaining fluorescence derives from pyrenes not intercalated between bases, but most likely bound externally. ODRS involves a double pulse sequence, where the pump laser excites the sample in a spectral region which is selectively absorbed by one component; the pump selectively excites this component out of its electronic ground state. A probe pulse monitors the Raman spectra of the remaining ground-state species in the sample, in this case selectively enriched in intercalated pyrene. The Raman intensities and enhancement patterns of the intercalated pyrene are very different from the external site bound pyrene. This new technique of ODRS permits us to selectively monitor pyrene molecules bound at two different sites of DNA and is a new general method for studying complex systems.