Division of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička Cesta 54, 10000 Zagreb, Croatia.
Department of Chemistry and Chemical Engineering/Chemistry and Biochemistry, Chalmers University of Technology, S-41296 Gothenburg, Sweden.
Molecules. 2020 May 7;25(9):2188. doi: 10.3390/molecules25092188.
We synthesized a new amino acid-fluorescent nucleobase derivative (qAN1-AA) and from it two new fluorescent nucleobase-fluorophore (pyrene) conjugates, whereby only the analogue with the longer and more flexible linker (qAN1-pyr2) self-folded into intramolecularly stacked qAN1/pyrene conformation, yielding characteristic, 100 nm-red-shifted emission (λ = 500 nm). On the contrary, the shorter and more rigid linker resulted in non-stacked conformation (qAN1-pyr1), characterized by the emission of free pyrene at λ = 400 nm. Both fluorescent nucleobase-fluorophore (pyrene) conjugates strongly interacted with ds-DNA/RNA grooves with similar affinity but opposite fluorescence response (due to pre-organization), whereas the amino acid-fluorescent base derivative (qAN1-AA) was inactive. However, only intramolecularly self-folded qAN1-pyr2 showed strong fluorescence selectivity toward poly U (Watson-Crick complementary to qAN1 nucleobase) and poly A (reverse Hoogsteen complementary to qAN1 nucleobase), while an opposite emission change was observed for non-complementary poly G and poly C. Non-folded analogue (qAN1-pyr1) showed no ss-RNA selectivity, demonstrating the importance of nucleobase-fluorophore pre-organization.
我们合成了一种新的氨基酸-荧光碱基衍生物 (qAN1-AA)，并由此得到了两种新的荧光碱基-荧光团 (芘) 缀合物，其中只有具有更长和更灵活连接子的类似物 (qAN1-pyr2) 自身折叠成分子内堆积的 qAN1/芘构象，产生特征性的、100nm 红移发射 (λ = 500nm)。相反，较短且刚性更强的连接子导致非堆积构象 (qAN1-pyr1)，其特征是自由芘的发射在 λ = 400nm。两种荧光碱基-荧光团 (芘) 缀合物与 ds-DNA/RNA 沟槽强烈相互作用，具有相似的亲和力但荧光响应相反 (由于预组织)，而氨基酸-荧光碱基衍生物 (qAN1-AA) 则没有活性。然而，只有分子内自折叠的 qAN1-pyr2 对聚 U（与 qAN1 碱基互补的沃森-克里克）和聚 A（与 qAN1 碱基反向 Hoogsteen 互补）显示出强烈的荧光选择性，而对非互补的聚 G 和聚 C 则观察到相反的发射变化。未折叠的类似物 (qAN1-pyr1) 对 ss-RNA 没有选择性，证明了碱基-荧光团预组织的重要性。
