Modified 2′-deoxyribonucleotide triphosphates (dNTPs) have widespread applications in both existing and emerging biomolecular technologies. For such applications it is an essential requirement that the modified dNTPs be substrates for DNA polymerases. To date very few examples of C5-modified dNTPs bearing negatively charged functionality have been described, despite the fact that such nucleotides might potentially be valuable in diagnostic applications using Si-nanowire-based detection systems. Herein we have synthesised C5-modified dUTP and dCTP nucleotides each of which are labelled with an dianionic reporter group. The reporter group is tethered to the nucleobase via a polyethylene glycol (PEG)-based linkers of varying length. The substrate properties of these modified dNTPs with a variety of DNA polymerases have been investigated to study the effects of varying the length and mode of attachment of the PEG linker to the nucleobase. In general, nucleotides containing the PEG linker tethered to the nucleobase via an amide rather than an ether linkage proved to be the best substrates, whilst nucleotides containing PEG linkers from PEG6 to PEG24 could all be incorporated by one or more DNA polymerase. The polymerases most able to incorporate these modified nucleotides included Klentaq, Vent(exo-) and therminator, with incorporation by Klenow(exo-) generally being very poor.
修改后的2'-脱氧核苷酸三磷酸盐(dNTPs)在现有和新兴的生物分子技术中具有广泛的应用。对于这些应用,修改后的dNTPs能够作为DNA聚合酶的底物是一个基本要求。迄今为止,尽管这些核苷酸可能在使用基于硅纳米线检测系统的诊断应用中具有潜在价值,但很少有负电荷官能团的C5-修饰dNTPs的例子被描述。在这里,我们合成了带有二阴离子报告基团的C5-修饰的dUTP和dCTP核苷酸,每个核苷酸都通过基于聚乙二醇(PEG)的链接物与核碱基标记。研究了这些修改后的dNTPs与各种DNA聚合酶的底物特性,以研究改变PEG连接物长度和连接模式对核碱基的影响。一般来说,含有通过酰胺而不是醚键连接到核碱基的PEG连接物的核苷酸被证明是最好的底物,而含有从PEG6到PEG24的PEG连接物的核苷酸都可以被一个或多个DNA聚合酶所合并。最能够合并这些修改后的核苷酸的聚合酶包括Klentaq、Vent(exo-)和therminator,而Klenow(exo-)的合并通常非常差。