Laboratory of Analytical Chemistry, Department of Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102a, HR-10000 Zagreb, Croatia.
Analyst. 2011 Aug 7;136(15):3185-93. doi: 10.1039/c0an01035a. Epub 2011 Jun 22.
Raman and surface-enhanced Raman spectra of new DNA/RNA-binding compounds consisting of three imidazole (Im) and three pyridine (Py) rings connected by tripodal polyaminomethylene linkages were obtained by the near-infrared excitation at 1064 nm. Study of interactions of Im and Py polyamines with single-stranded RNA polynucleotides (poly A, poly G, poly C, poly U), double-stranded DNA polynucleotides (poly dAdT-poly dAdT, poly dGdC-poly dGdC) and calf thymus DNA (ct-DNA) by surface-enhanced Raman spectroscopy (SERS) reveals unambiguous enhancement of the Raman scattering from the small molecules as well as appearance of new bands in spectra associated mainly with nucleobases. The SERS experiments point toward comparable interactions of Im and Py polyamines with single-stranded purine and pyrimidine polynucleotides. Furthermore, SERS experiments with double stranded polynucleotides reveal the base-pair dependent selectivity of Im and Py, whereby interactions within both, major and minor groove are indicated for poly dAdT-poly dAdT, at variance to preferred binding of Im and Py to only major groove of poly dGdC-poly dGdC. SERS spectra of Im and Py with ct-DNA imply that protonated amino groups of these compounds preferentially interact with N7 atoms (adenine, guanine) while nitrogen in aromatic rings of polyamines might be attracted to C6-NH(2) (adenine), all sites being located at the major groove of the DNA helix. Wavenumber downshift of the imidazole (Im) and pyridine (Py) ring vibrations supports aromatic stacking interactions of imidazole and pyridine aromatic moieties with DNA base-pairs.
通过近红外 1064nm 激发，获得了由三个咪唑（Im）和三个吡啶（Py）环通过三足多胺亚甲基连接而成的新型 DNA/RNA 结合化合物的拉曼和表面增强拉曼光谱。通过表面增强拉曼光谱（SERS）研究了 Im 和 Py 多胺与单链 RNA 多核苷酸（poly A、poly G、poly C、poly U）、双链 DNA 多核苷酸（poly dAdT-poly dAdT、poly dGdC-poly dGdC）和小牛胸腺 DNA（ct-DNA）的相互作用，明确增强了小分子的拉曼散射，并在与核碱基主要相关的光谱中出现了新的谱带。SERS 实验表明，Im 和 Py 多胺与单链嘌呤和嘧啶多核苷酸的相互作用相当。此外，双链多核苷酸的 SERS 实验揭示了 Im 和 Py 的碱基对依赖性选择性，表明在 poly dAdT-poly dAdT 中存在碱基对依赖性的多胺内、小沟相互作用，而在 poly dGdC-poly dGdC 中仅优先结合 Im 和 Py 到大沟。Im 和 Py 与 ct-DNA 的 SERS 光谱表明，这些化合物的质子化氨基基团优先与 N7 原子（腺嘌呤、鸟嘌呤）相互作用，而多胺的芳环中的氮可能被吸引到 C6-NH(2)（腺嘌呤），所有这些位点都位于 DNA 螺旋的大沟中。咪唑（Im）和吡啶（Py）环振动的波数下移支持了 Im 和 Py 芳环部分与 DNA 碱基对的芳构堆积相互作用。
