Peptide nucleic acid (PNA) is a mimic of nucleic acids that is able to bind complementary oligonucleotides with high affinity and excellent selectivity. As such, the use of PNA has been proposed in numerous applications in biochemistry, medicine, and biotechnology. Sequences of pseudo-complementary PNAs containing diaminopurine (D)-2-thiouracil (^SU) base pairs bind to complementary regions within double-stranded DNA targets. This type of binding is termed “double duplex invasion” and involves unwinding of the duplex accompanied by simultaneous hybridization of both DNA strands by the two pseudo-complementary PNAs. In this study, a simple method of assaying DNA strand invasion by pseudo-complementary PNAs was developed. This method is based on the incorporation of a single fluorescent cytidine analog, phenylpyrrolocytidine (PhpC), into the double-stranded DNA target such that upon invasion by PNA, the PhpC is displaced to a single-stranded region resulting in the turn-on of fluorescence emission. This fluorescent assay is applicable to studies both at equilibrium and approach-to-equilibrium (time-dependent) conditions.

中文翻译：

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一种检测肽核酸定向双链双链体侵袭的简单荧光测定法

肽核酸 (PNA) 是核酸的模拟物，能够以高亲和力和优异的选择性结合互补寡核苷酸。因此，已在生物化学、医学和生物技术的众多应用中提出使用 PNA。含有二氨基嘌呤 (D)-2-硫氧嘧啶 ( ^{S ) 的假互补 PNA 序列}U) 碱基对与双链 DNA 靶标内的互补区域结合。这种类型的结合被称为“双双链侵入”，涉及双链的解旋，同时两条 DNA 链被两条假互补的 PNA 杂交。在本研究中，开发了一种通过伪互补 PNA 测定 DNA 链侵袭的简单方法。该方法基于将单个荧光胞苷类似物苯基吡咯胞苷 (PhpC) 掺入双链 DNA 靶标中，这样当 PNA 入侵时，PhpC 被置换到单链区域，导致荧光发射。这种荧光测定适用于平衡和接近平衡（时间依赖性）条件下的研究。