ULTRAVIOLET RESONANCE RAMAN-SPECTROSCOPY OF THE NUCLEOTIDES WITH 266-NM, 240-NM, 218-NM, AND 200-NM PULSED LASER EXCITATION
ULTRAVIOLET RESONANCE RAMAN-SPECTROSCOPY OF THE NUCLEOTIDES WITH 266-NM, 240-NM, 218-NM, AND 200-NM PULSED LASER EXCITATION
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DOI：
10.1021/ja00292a012
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发表时间：
1985-01-01
影响因子：
15
通讯作者：
SPIRO, TG
中科院分区：
文献类型：
--
作者：
FODOR, SPA;RAVA, RP;SPIRO, TG
本文报道了DUMP、DTMP、dCMP、dGMP和DAMP在稀溶液中的紫外共振拉曼光谱。10-3M)水溶液。用四倍频激光(266 Nm)和H2喇曼移位器在第一、第二和第三反斯托克斯谱线上产生了266、240、218和200 nm的激发光。由于嘌呤和嘧啶环的面内模式，光谱包含了振动带，并在增强模式中显示了4个波长之间的较大变化。这些变化有助于分辨重叠的条带和进行分配(例如，1674和1686厘米-1处的转储C4.dd.O和C2.bd.O伸展)。根据模式分配(从以前的简正坐标计算)和从以前的CNDO[完全忽略微分重叠]计算得出的激发态的特征，讨论了这些增强。对于Dump和DTMP，增强是根据分别基于长波长和短波长的C6.dbd.C5-C4.dbd.O和C2.dbd.O片段的电子跃迁共振来解释的。然而，1230(转储)和1244(DTMP)cm-1处的谱带强度是异常的，表明需要进行正常模式修订。对于dGMP和DAMP，其强度在整个紫外区符合N7×C8局域长波跃迁和一系列基于三烯的跃迁。对dGMP提出了一个振动(B项)增强的例子，与215 nm处的弱跃迁共振。报道了DTMP、dCMP、dGMP和DAMP等摩尔混合物的RR谱，并在每个波长确定了主要贡献者。增强变异有望在核酸的RR谱中分离出与单个碱基相关的关键带。
UV resonance Raman [RR] spectra are reported for dUMP, dTMP, dCMP, dGMP and dAMP in dilute (5 .times. 10-3 M) aqueous solution. Excitation (266, 240, 218 and 200 nm) was generated with a frequency-quadrupled Nd:YAG laser (266 nm) and a H2 Raman shifter operated at the first, second and third anti-Stokes lines. The spectra contain vibrational bands due to the in-plane modes of the purine and pyrimidine rings and show large alterations among the 4 wavelengths in the enhancement patterns. These changes are helpful in resolving overlapped bands and making assignments (e.g., of the dUMP C4.dbd.O and C2.dbd.O stretches, at 1674 and 1686 cm-1). The enhancements are discussed in the light of mode assignments (from previous normal coordinate calculations) and the character of the excited states, as deduced from previous CNDO [complete neglect of differential overlap] calculations. For dUMP and dTMP the enhancements are interpreted in terms of resonance with electronic transitions based on the C6.dbd.C5-C4.dbd.O and C2.dbd.O fragments at long and short wavelengths, respectively. However, the strengths of bands at 1230 (dUMP) and 1244 (dTMP) cm-1 are anomalous and suggest a need for normal mode revisions. For dGMP and dAMP, the intensities are consistent with a N7.dbd.C8 localized transition at long wavelengths and a series of triene-based transitions throughout the UV region. An instance of vibronic (B term) enhancement is suggested for dGMP, in resonance with a weak transition at 215 nm. RR spectra are reported for an equimolar mixture of dTMP, dCMP, dGMP and dAMP, and the major contributors are identified at each wavelength. The enhancement variations give promise for isolating the key bands associated with the individual bases in RR spectra of nucleic acids.