作者:Lital Zilbershtein、Alon Silberman、Bilha Fischer
DOI:10.1039/c1ob05681f
日期:——
Natural nucleotides are not useful as fluorescent probes because of their low quantum yields. Therefore, a common methodology for the detection of RNA and DNA is the application of extrinsic fluorescent dyes coupled to bases in oligonucleotides. To overcome the many limitations from which fluorescent nucleotide–dye conjugates suffer, we have developed novel purine nucleosides with intrinsic fluorescence to be incorporated into oligonucleotide probes. For this purpose we synthesized adenosine and guanosine fluorescent analogues 7–25, conjugated at the C8 position with aryl/heteroaryl moieties either directly, or via alkenyl/alkynyl linkers. Directly conjugated analogues 7–14, exhibited high quantum yields, ϕ >0.1, and short λem (<385 nm). Alkynyl conjugated analogues 22–25, exhibited low quantum yields, ϕ <0.075, and λem<385 nm. The alkenyl conjugated analogues 15–21, exhibited λem 408–459 nm. While analogues 15,16, and 20 bearing an EDG on the aryl moiety, exhibited ϕ <0.02, analogues 17, and 21 with EWG on the aryl moiety, exhibited extremely high quantum yields, ϕ ≈ 0.8, suggesting better intramolecular charge transfer. We determined the conformation of selected adenosine analogues. Directly conjugated analogue 8 and alkynyl conjugated analogue 22, adapted the syn conformation, whereas alkenyl conjugated analogue 15 adapted the anti conformation. Based on the long emission wavelengths, high quantum yields, anti conformation and base-paring compatibility, we suggest analogues 17 and 21 for further development as fluorescent probes for the sensitive detection of genetic material.
天然核苷酸由于量子产率低,不能用作荧光探针。因此,检测 RNA 和 DNA 的常用方法是应用与寡核苷酸中碱基偶联的外在荧光染料。为了克服荧光核苷酸-染料共轭物所受到的诸多限制,我们开发了具有内在荧光的新型嘌呤核苷,并将其加入寡核苷酸探针中。为此,我们合成了腺苷和鸟苷荧光类似物 7-25,它们在 C8 位直接或通过烯基/炔基连接物与芳基/杂芳基共轭。直接共轭的类似物 7-14 显示出较高的量子产率,ϕ>0.1,λem 较短(<385 nm)。炔基共轭类似物 22-25 的量子产率较低,j <0.075,λem <385 nm。烯基共轭类似物 15-21 的 λem 波长为 408-459 纳米。芳基上带有 EDG 的类似物 15、16 和 20 的 ϕ <0.02,而芳基上带有 EWG 的类似物 17 和 21 的量子产率极高,ϕ ≈ 0.8,表明分子内电荷转移更好。我们测定了部分腺苷类似物的构象。直接共轭类似物 8 和炔基共轭类似物 22 呈合构象,而烯基共轭类似物 15 呈反构象。由于类似物 17 和 21 具有发射波长长、量子产率高、反构象和碱基相容等特点,我们建议将它们进一步开发为荧光探针,用于灵敏地检测遗传物质。