Ferrocene-peptide adducts for DNA binding: Towards sequence-selective electrochemical DNA sensors

DNA对地球上的生命至关重要，因为它包含了定义任何生物特征的遗传信息，从浮游生物到人类。它是由称为核碱基的更小的构建块序列组成的。这个序列既定义了DNA所包含的遗传密码，也定义了它的物理结构，最常见的是双螺旋-有点像梯子，盘绕成螺旋形。科学家们已经成功地解码了人类DNA的整个序列，从而能够将特定的基因（DNA序列的离散片段）与特定的疾病联系起来。这提供了选择性地识别致病基因并提供新疗法的可能性。然而，由于仅人类基因组就包含约20，000个基因，因此能够选择性地和可靠地识别并发出单个基因存在的信号非常重要。传感器通常由两部分组成：对目标具有高度选择性的识别单元，以及允许可测量和可量化输出的报告基团。化学家在开发用于分析小分子（例如污染物和药物分子）的传感器方面取得了重大成功。然而，这些分子通常在原子水平上与传感器相互作用，而DNA和其他生物分子的相互作用水平比这大10倍，因此需要开发一类新的传感器，大自然使用DNA结合蛋白来“读取”存储在DNA序列中的遗传信息。蛋白质是由称为氨基酸的较小构建块组成的长链，它们折叠成明确的结构，这对生物分子识别很重要。虽然这些蛋白质是大而复杂的分子，但大多数蛋白质使用相对较小的螺旋序列结合到双螺旋DNA的大沟上，该螺旋序列是圆柱形的。我们的目的是通过制备来自DNA结合螺旋的最低限度的蛋白质序列，在一个明显更简单（易于合成）的系统中捕获这种DNA结合强度和选择性。然后将其与化学报告基团偶联，为用户提供对DNA结合敏感的可测量输出。由于其有吸引力的性质和易于修改，二茂铁是我们的报告基团的选择。我们建议使用一个核心二茂铁单元，并将其与两个DNA结合螺旋偶联，这两个DNA结合螺旋将取自蛋白质GCN 4。这种偶联将通过半胱氨酸的侧链实现，半胱氨酸是一种天然氨基酸，我们将其引入GCN 4序列。这种合成将导致新的，序列选择性的DNA生物传感器的发展，并提供了一种方法，这是更广泛的application.These微型二茂铁蛋白质生物传感器将提供优于目前的DNA传感器，因为它们将能够选择特定的序列和双螺旋DNA。其他优势包括能够模拟DNA结合蛋白的生物功能，同时提供信号输出，使我们能够监测真实的时间发生的重要生物过程。这些新的传感器将推动对自然如何识别DNA中基因的理解，并在这样做的过程中将大大有助于开发新的医学治疗和诊断方法。

DNA is crucial to life on earth, as it contains the genetic information which defines the characteristics of any living thing, from plankton to humans. It is made up of sequences of smaller building blocks, called nucleobases. This sequence defines both the genetic code the DNA contains and also its physical structure, which is most commonly a double helix - a bit like a ladder, coiled into a spiral. Scientists have successfully decoded the entire sequence of human DNA and in turn have been able to link specific genes - discrete stretches of a DNA sequence - to particular diseases. This offers the potential to selectively identify genes which cause disease and offer new therapies. However, as the human genome alone contains around 20,000 genes, it is very important to be able to selectively and reliably recognise and signal the presence of individual genes. The type of molecule or device that allows us to do this is called a Sensor.Sensors typically comprise two parts; recognition units which are highly selective for the desired target, and a reporter group which allows a measureable and quantifiable output. Chemists have had significant success in developing sensors to analyse small molecules, for instance pollutants and drug molecules. However, these molecules typically interact with sensors on the atomic level, whereas DNA and other biomolecules interact at a level 10 times larger than this, so a new class of sensor needs to be developed.Nature uses DNA-binding proteins to "read" the genetic information stored in the DNA sequence. Proteins are long chains of smaller building blocks called amino acids that fold into well-defined structures, which are important for biomolecular recognition. Though these proteins are large and complicated molecules, the majority bind to the major groove of double helix DNA using a relatively small helical sequence, which is cylindrical in shape. It is our intention to capture this DNA binding strength and selectivity in a significantly simpler (easily synthesised) system, by preparing a minimalist protein sequence derived from a DNA-binding helix. This will then be coupled to a chemical reporter group to provide the user with a measurable output sensitive to DNA binding. Due to its attractive properties and ease of modification, ferrocene is our reporter group of choice. We propose to use a core ferrocene unit and couple it to two DNA-binding helices which will be taken from the protein GCN4. This coupling will be achieved through the side chain of cysteine, a natural amino acid which we will introduce into the GCN4 sequence. This synthesis will lead to the development of novel, sequence-selective DNA biosensors, and provide an approach which is more widely applicable.These miniature ferrocene-protein biosensors would offer advantages over current DNA sensors as they would be capable of selecting for both particular sequences and for double helix DNA. Other advantages would include being able to mimic the biological function of the DNA binding protein from which the sensor is derived, while providing a signal output, allowing us to monitor important biological processes taking place in real time.These new sensors will drive increased understanding of how nature recognises genes within DNA, and in doing so will contribute greatly to efforts to develop new medical treatments and diagnostics.