Writing through catalysis: A tape-reading molecular catalyst

1936年，艾伦·图灵发表了用于抽象计算的自动机器的概念。现在被称为“图灵机”，他的提议设想了一种设备，其特点是有一个“头”，可以在磁带上移动时读写符号。这一影响深远的思维实验引发了计算机科学的发展。尽管现代计算机使用了一种不同的设计，使用了随机存取存储器，但图灵的自动机器与生物学中的信息处理有着惊人的相似之处(例如，通过核糖体读取和写入信息。最近，Leigh团队报道了一种人造分子机器，它通过化学燃料沿分子带定向传输，随着沿途遇到的带上的手性中心改变读取头的构象。构象变化导致磁头的圆二向色性响应的变化，因此分子带上的符号序列可以根据变化的CD响应作为数据串读出(280 nm处的+ve Cotton效应对应于数字+1；-ve Cotton效应对应于-1，无Cotton效应对应于0)。这个项目将寻求将这一概念扩展到通过催化来写入信息，使用构象的变化来改变读头在轨道上移动时不对称催化的利手性。我们将首先通过分步操作(例如，使用如下所示的Trost类配体)来研究这一概念，并最终将其扩展到具有编码序列信息的聚合物的合成，这是一项类似于核糖体执行的任务。开发一种人造催化剂，当其沿信息编码的轨道定向移动时，改变催化转化的立体化学结果，这将是人工分子机械和催化领域的一项里程碑式的成就。它将使分子信息从一种形式(原始磁带)转化为另一种形式。这将类似于核糖体执行的功能，但在一个完全人工的系统中，不仅限于多肽，而且以立体化学为特征，而不是核苷酸密码子。从这个项目中获得的知识将在不同的领域产生影响。除了潜在地改进合成催化剂的设计外，这一结果还可能导致新的、人工的、类似酶的催化剂的设计。

In 1936 Alan Turing published a concept for an automatic machine for abstract computing. Nowadays called a 'Turing machine', his proposal envisaged a device that featured a 'head' that could read and write symbols while moving along a tape. This influential thought experiment sparked the development of computer science. Although modern computers use a different design that employs random access memory, the resemblance of Turing's 'automatic machine' to information processing in biology is striking (the reading and writing of information by the ribosome, for example. Recently, the Leigh group reported an artificial molecular machine that is transported directionally along a molecular tape by chemical fuelling, changing the conformation of the reading head in response to chiral centres on the tape it encounters along the way. The conformational change results in changes to the circular dichroism response of the head, and so the sequence of symbols on the molecular tape can be read out as a string of data according to the changing CD response (+ve Cotton effect at 280 nm corresponds to the digit +1; -ve Cotton effect to -1, no Cotton effect to 0). This project will seek to extend this concept to the writing of information through catalysis, using the change in conformation to alter the handedness of asymmetric catalysis by the reading head as it moves along the track. We will first investigate this concept through step-wise operations (e.g. with Trost-like ligands, as depicted below) and, ultimately, extend it to the synthesis of polymers with encoded sequence information, a task analogous to that performed by the ribosome.The development of an artificial catalyst that changes the stereochemical outcome of catalytic transformations as it moves directionally along an information-encoded track would be a landmark achievement for the fields of both artificial molecular machinery and catalysis. It would enable the translation of molecular information from one form (the original tape) to another. This would be analogous to the function performed by the ribosome, but in a wholly artificial system not limited to peptides and featuring the reading of stereochemistry rather than nucleotide codons. The knowledge gained in this project will have impact in different areas. In addition to potentially improving the design of synthetic catalysts, the results may lead to the design of new, artificial, enzyme-like catalysts.