Biocatalytic Approaches to the Synthetic Manipulation of Silicones

从骨骼到细胞，生物体构建了各种各样的结构，大小不一。然而，这种结构的组装最终依赖于基本在分子到纳米尺度（埃到纳米）上的构建块的组织和生产。这些结构由各种化合物（蛋白质、脂肪、DNA）组成，由酶合成。这些酶是所有生物体的分子机制，它们特别有趣，因为它们能够高效地进行各种反应，主要产生所需的化合物，很少产生不需要的副产物。此外，它们在环境条件下工作，不依赖于稀有或有毒材料。因此，许多类型的酶现在被用于药品和其他高价值化学品的生产。到目前为止，酶尚未被广泛研究的一个领域是含硅有机化合物的化学性质。这种“有机硅”化合物主要以“硅酮”的形式使用，这是一种类似塑料的材料。这些有机硅极其广泛地应用于人类活动的各个领域，从工业机器零件、润滑剂和密封剂；家居用品、化妆品和油漆等消费品；还有电子和外科设备。事实上，这些材料在经济上非常重要，全球有机硅的生产和使用每年带来数十亿英镑的营业额。不幸的是，目前生产有机硅的方法依赖于含氯的原料，这些原料对生态不友好，而且生产时需要消耗能源。相比之下，一些海洋海绵使用硅（以玻璃状二氧化硅的形式）作为其骨骼的一部分。为了形成这个骨架，海绵使用了一种叫做“硅蛋白”的酶家族，这种酶能够与二氧化硅反应。首席研究员最近的研究表明，值得注意的是，这些酶能够在相对温和的条件下（低于100摄氏度，使用无毒的起始材料）催化一系列有机硅化合物的形成和降解。因此，这些酶有可能提供一种可持续的生产有机硅化合物的方法，这种方法将在化学工业的许多领域得到应用。此外，硅蛋白还可以用于将不需要的硅废物分解成可回收的化合物，这是目前使用传统化学方法无法实现的。因此，本研究的目标是研究利用硅蛋白高效、精确合成有机硅材料的可行性，并开发出能够生产具有多种化学结构的有机硅的酶的改性版本。将针对的有机硅类型既包括适用于工业应用的有机硅，也包括难以通过其他方法合成的新型有机硅。同时，还将研究它们在有机硅后处理和循环利用中的可行性。在所有情况下，本研究的主要部分将是研究硅酸盐蛋白能够进行这些反应的化学机制。因此，对这些酶如何发挥作用的理解将使我们能够进行修改以提高它们的能力。

Living organisms construct a tremendous variety of structures across a wide range of sizes, from bones to cells. Yet, the assembly of such structures ultimately rely on the organisation and production of building blocks that are essentially on the molecular to nanoscopic scale (Angstroms to nanometres). These structures, which are composed from a variety of compounds (proteins, fats, DNA) are synthesised by enzymes. These enzymes, which are the molecular machinery of all living organisms, are particularly interesting since they are able to perform a variety of reactions with high efficiency, giving mainly the desired compound with few unwanted by-products. Furthermore, they function under ambient conditions and do not rely on rare or toxic materials. As a result, many types of enzymes are now utilised in the production of medicines and other high-value chemicals.One area in which enzymes have not been widely studied so far is in the chemistry of organic compounds containing silicon. Such "organosilicon" compounds are mainly used in the form of "silicone", a plastic-like material. These silicones are extremely widely used in all sectors of human activity, from industrial machine parts, lubricants and sealants; to consumer goods such as homeware, cosmetics and paints; as well as in electronic and surgical devices. Indeed, these materials are economically very important, with the global production and use of silicones giving rise to a multi-£billion turnover annually.Unfortunately, current methods of producing silicones rely on chlorine-containing raw materials that are ecologically unfriendly and energy demanding to produce. In contrast, some species of marine sponges use silicon (in the form of glass-like silica) as part of their skeleton. To form this skeleton, the sponges employ a family of enzymes called "silicateins", which are able to react with silica. Recent research by the lead investigator has shown that, remarkably, these enzymes are able to catalyse the formation, as well as degradation, of a range of organosilicon compounds under relatively mild conditions (less than 100 degrees C, using non-toxic starting materials). Thus, these enzymes could potentially offer a sustainable means of producing silicone compounds that would find use in many areas of the chemical industry. Furthermore, the silicateins could also be applied to decompose unwanted silicone waste into compounds that could be recycled, which cannot currently be achieved using conventional chemical methods.Accordingly, the goals of this research are to investigate the feasibility of using silicateins for the efficient and precise synthesis of silicone materials, and develop modified versions of the enzymes that will be able to perform the production of silicones with a variety of chemical structures. The types of silicones that will be targeted include both silicones that are applicable to industrial applications, but also novel types that are otherwise difficult to synthesise by other means. In parallel, the feasibility of using them in the reprocessing and recycling of silicones will also be researched. In all cases, a major part of this research will be to study the chemical mechanisms by which the silicateins are able to perform these reactions. Such an understanding of how these enzymes function will therefore allow us to make modifications to improve their capabilities.