Bacterial hydrogenases for biohydrogen technology

氢气是未来能源需求的一篮子解决方案之一。目前，99%的氢气是通过重整化石燃料生产的，1%的氢气来自电解。大多数被工业直接使用，但越来越多地被用作燃料。氢的单位重量能量是所有燃料中最高的，而且它的使用(特别是在燃料电池中)是清洁和高效的。作为通过光解(阳光)或可再生能源电解使水充满能量的直接产物，氢是最绿色和最可再生的燃料。这一事实正在吸引发达国家的大量研究资金，特别是美国、澳大利亚、德国和瑞典。氢气的缺点经常被人提起--低能量密度、存储困难(这对小型汽车来说是一个劣势)、原始的供应和分配基础设施--但这些问题不能阻碍它的发展，氢气最终将成为人类生活和经济中重要的、甚至占主导地位的部分。生物氢是生物体产生或氧化的氢。建设性地利用这一资源的范围是巨大的；然而，氢也是病原体的营养物质。氢气是植物根瘤中的微生物利用一种称为固氮酶的酶(催化剂)合成氨的副产品。氢也是由多种微生物产生和用作燃料的。这种化学依赖于被称为氢酶的氧气敏感酶，这种酶对许多微生物世界都是必不可少的，包括严格的土壤需氧菌、可以适应产生氢的绿藻、甲烷生产者，以及一些臭名昭著的人类病原体，如螺杆菌和沙门氏菌。事实上，氢酶的效率对细菌的毒力至关重要。我们和其他人提出，氢酶的活性部位与铂一样活跃--铂是一种昂贵而有限的资源。这引起了人们对它们作为电子/燃料电池/传感器设备中实际或鼓舞人心的催化剂的开发的兴趣。因此，了解并因此能够控制细胞内氢酶的活性和耐氧性是带来未来、完全可再生和健康的氢能技术的最重要因素之一。牛津大学和邓迪大学的实验室具有极强的互补性。邓迪团队在研究常见肠道细菌大肠杆菌和臭名昭著的病原体沙门氏菌中氢酶的细胞生物学方面拥有国际公认的专业知识。牛津小组开创了一种研究氢酶的物理方法，快速而准确地揭示了氢酶的所有重要催化性质。这种方法是一种被称为蛋白质膜电化学的电化学技术，它涉及到将酶附着在电极表面。获得的准确数据有助于指导进一步的研究，节省了全世界花费在开发生物氢上的大量研究时间和资金。酶分子与电极的连接类似于将其连接到电路上，在这个过程中，酶能够起到实际的电催化剂的作用，能够从氢气中产生电能，或者从电或光中产生氢气(如果酶被连接到光敏粒子上)。

Hydrogen gas is among a 'basket of solutions' for future energy needs. At present 99% of hydrogen is produced by reforming fossil fuels and 1% comes from electrolysis. Most is used directly by industry, but increasingly it is being used as a fuel. Hydrogen has the highest energy per weight of any fuel, and its use (particularly in a fuel cell) is clean and efficient. As the immediate product of energizing water by photolysis (sunlight) or renewable-powered electrolysis, hydrogen is the 'greenest' and most renewable of fuels. This fact is attracting major research funding in advanced countries, particularly USA, Australia, Germany and Sweden. The drawbacks of hydrogen are frequently voiced - low energy density, difficulty in storage (a disadvantage for small vehicles), primitive supply and distribution infrastructure - but these issues cannot hold back its development, and H2 will eventually be an important and even dominant part of human lives and economies. Biohydrogen is the production or oxidation of hydrogen by organisms. The scope for tapping into this resource constructively is enormous; yet hydrogen is also a nutrient for pathogens. Hydrogen is a byproduct of ammonia synthesis by microorganisms contained in plant root nodules, using an enzyme (catalyst) known as nitrogenase. Hydrogen is also produced and used as a fuel by a vast range of microorganisms. The chemistry depends upon oxygen-sensitive enzymes known as hydrogenases, which are essential to much of the microbial world, including strict soil aerobes, green algae that can be adapted to produce hydrogen, methane-producers, and some notorious human pathogens such as Helicobacter and Salmonella. Indeed, the efficiency of hydrogenases is crucial to bacterial virulence. We and others have proposed that the active sites of hydrogenases are as active as platinum - an expensive and limited resource. This has raised interest in their exploitation as actual or inspirational catalysts in electronic/fuel cell/sensor devices. Understanding and consequently being able to control the activity and oxygen-tolerance of hydrogenases within the cell are therefore among the most important factors in bringing about a future, fully renewable, and healthy H2 energy technology. The Oxford and Dundee laboratories are superbly complementary. The Dundee group has internationally-recognised expertise in studying the cell biology of hydrogenases in the common gut bacterium E. coli and the notorious pathogen, Salmonella. The Oxford group have pioneered a physical method for studying hydrogenases, which reveals, rapidly and accurately, all of their important catalytic properties. The method is an electrochemical technique known as protein film electrochemistry, and it involves the enzyme being attached to an electrode surface. The precise data that are obtained help guide further investigations, saving large amounts of research time and money that is spent worldwide on developing biohydrogen. The attachment of the enzyme molecule to an electrode is analogous to 'wiring' it to an electrical circuit, and in the process the enzyme is able to function as a practical electrocatalyst, able to produce electricity from hydrogen or hydrogen from electricity or light (if the enzyme is attached to light-sensitive particles).