New routes to driving enzyme-catalysed chemical synthesis using hydrogen gas

细菌细胞就像微型的化学工厂，已经进化出专门的路线来制造我们用作药物、芳香剂、食品添加剂或农业化学品的许多分子。细胞中完成这项工作的关键部分是酶。打破细胞并分离出制造特定分子的酶是可能的。细菌也可以被改造成人造化学物质，扩大它们可以产生的分子范围。现在已经建立了大规模培养细菌和分离大量酶的程序，与此同时，化学公司开始意识到使用酶代替传统化学途径的好处。在复杂分子的生产中，如药物、香料和食品调味品，酶产生的废物要少得多，可以制造更纯净的化学产品，并且可以在水中进行化学反应，而不是在有毒、污染的溶剂中进行。在食品和制药工业中，最终产品的纯度尤其重要，因为污染物可能具有严重的有害影响。尽管人们对在化学生产中使用酶催化越来越感兴趣，但在这种方法被广泛采用之前，仍有许多挑战需要克服。酶一旦从细胞中分离出来，通常是相当不稳定的。它们的稳定性可以通过附着在表面来提高，但这通常需要复杂的附着过程，而且价格昂贵。其次，许多酶只有在被称为辅因子的特殊辅助分子存在的情况下才能起作用，辅因子在制造化学物质的过程中被酶消耗殆尽。辅因子也很昂贵，为了使酶处理在经济上可行，必须有一些回收辅因子的方法。不幸的是，目前可用的回收辅因子的方法会产生更多的废物，从而污染所需的化学产品。我们已经开发了一种技术，解决了这两个挑战，为酶催化提供了急需的步骤改变。目前，我们的技术只在我们的实验室中进行了小规模的演示，但我们现在需要说服化学、制药和食品工业，这为未来的化学生产提供了真正的好处。我们的技术是这样的：一旦我们从细菌细胞中分离出酶，我们立即将它们附着在廉价的碳珠上。这是一个非常简单的一步过程。我们将几种不同类型的酶附着在每个头上，这样酶就可以一起工作来完成制造化学品的每一步。我们为这些小珠子提供低、安全水平的氢气，这为回收辅因子提供了能量，并驱动酶机制来制造所需的化学物质。为了制造一种理想的化学物质，我们首先把一种便宜的化学积木放在水中，我们把一点氢气泡进去，加入我们的酶修饰的珠子，几个小时后，我们想要的化学产品就可以收集了！酶修饰的小球可以很容易地从反应混合物中舀出，除了所需的产物和微量的无害辅因子外，什么也不留下。作为额外的好处，这些珠子可以被收集和重复使用多次，最大限度地降低了使用酶的成本。为了将我们的概念从实验室规模的想法转变为工业采用的技术，我们需要证明我们可以大规模生产这种酶。我们需要证明这些珠子产生化学物质的速度有多快，以及产品的纯度有多高。这个项目将回答这些问题，因此在5年结束时，我们可以说服潜在的客户（化学，制药和食品添加剂公司），我们的技术将使他们以更低的成本和更环保的方式生产化学品。

Bacterial cells act as miniature chemical factories and have evolved specialised routes to making many of the sorts of molecules that we use as pharmaceuticals, pleasant fragrances, food additives or chemicals for use in agriculture. The key parts of the cells for carrying out this work are the enzymes. It is possible to break cells open and isolate an enzyme for making a specific molecule. Bacteria can also be engineered to make artificial chemicals, expanding the range of molecules they can produce. Procedures are now well-established for growing bacteria on a large scale and isolating large quantities of enzymes, and at the same time, chemical companies are starting to realise the benefits of using enzymes instead of traditional chemical routes. In the production of complicated molecules such as drugs, fragrances and food flavourings, enzymes generate much less waste, make purer chemical products, and allow chemistry to be carried out in water rather than toxic, polluting solvents. The purity of the end product is particularly important in the food and pharmaceutical industries where contaminants may have serious, harmful effects. Although there has been increasing interest in using enzyme catalysis in chemical production, many challenges remain to be overcome before this approach can be widely adopted. Once isolated from their cells, enzymes are often quite unstable. Their stability can be improved by attaching them to surfaces, but this often requires complicated attachment processes and can be expensive. Secondly, many enzymes only work in the presence of special helper-molecules called cofactors which are used up by the enzymes in the process of making chemicals. The cofactors are also expensive, and for enzyme processes to be economically viable, it is essential to have some way of recycling the cofactors. Unfortunately, the currently-available methods for recycling the cofactors make even more waste which contaminates the desired chemical products. We have developed a technology that addresses both of these challenges, offering a much-needed step change for enzyme catalysis. At the moment, our technology has only been demonstrated on a small scale in our laboratories, but we now need to convince the chemical, pharmaceutical and food industries that this offers real benefits for the future of chemical production. Our technology works as follows: once we have isolated enzymes from the bacterial cells, we immediately attach them onto cheap carbon beads. This is a very simple one-step process. We attach several different types of enzyme to each bead so that the enzymes can work together to carry out each step in making chemicals. We supply the beads with low, safe levels of hydrogen gas, and this provides the energy for recycling the cofactors and to drive the enzyme machinery necessary to make the required chemicals. To make a desired chemical, we start by putting a cheap chemical building-block in water, we bubble in a little hydrogen gas, add our enzyme-modified beads, and after a few hours, the desired chemical product is ready to collect! The enzyme-modified beads can be easily scooped out of the reaction mixture, leaving nothing else except the desired product and a tiny trace of the harmless cofactor. As an added bonus, the beads can be collected and re-used a number of times, minimising the cost of using enzymes. To take our concept from a lab-scale idea to a technology ready for industry to adopt, we need to show that we can produce the enzymes on a large scale. We need to show how quickly the beads can produce chemicals, and how pure the products are. This project will answer these sort of questions, so that at the end of the 5 years, we can convince potential customers (chemical, pharmaceutical and food additive companies) that our technology will allow them to make chemicals more cheaply and in a more environmentally-friendly way.