Bacterial hydrogenases for biohydrogen technology

氢气是未来能源需求的“一揽子解决方案”之一。目前，99%的氢气是通过重整化石燃料生产的，1%来自电解。大多数直接用于工业，但越来越多地用作燃料。氢是所有燃料中单位重量能量最高的，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）或可再生能源电解来激发水的直接产品，氢气是“最绿色”和最可再生的燃料。这一事实吸引了发达国家，特别是美国、澳大利亚、德国和瑞典的大量研究资金。氢的缺点经常被提及-能量密度低，难以储存（小型车辆的缺点），原始的供应和分配基础设施-但这些问题无法阻止其发展，H2最终将成为人类生活和经济的重要甚至主导部分。生物氢是由生物体产生或氧化氢。建设性地利用这一资源的空间是巨大的;然而氢也是病原体的营养素。氢是由植物根瘤中的微生物使用被称为固氮酶的酶（催化剂）合成氨的副产品。氢气也可以由大量的微生物产生并用作燃料。这种化学反应依赖于一种对氧敏感的酶，即氢化酶，它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、能够产生氢气的绿色藻类、甲烷生产菌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，氢化酶的效率对细菌的毒力至关重要。我们和其他人提出，氢化酶的活性位点和铂一样活跃--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/传感器设备中的实际或启发性催化剂的开发的兴趣。因此，了解并因此能够控制细胞内氢化酶的活性和耐氧性是实现未来完全可再生和健康的H2能源技术的最重要因素之一。牛津实验室和邓迪实验室是极好的互补。邓迪小组在研究肠道细菌E.大肠杆菌和臭名昭著的沙门氏菌。牛津大学的研究小组开创了一种研究氢化酶的物理方法，该方法快速准确地揭示了它们所有重要的催化特性。该方法是一种被称为蛋白质膜电化学的电化学技术，它涉及将酶附着在电极表面。所获得的精确数据有助于指导进一步的研究，节省了全球用于开发生物氢的大量研究时间和资金。将酶分子附着到电极上类似于将其“布线”到电路上，并且在此过程中，酶能够充当实用的电催化剂，能够从氢产生电或从电或光产生氢（如果酶附着到光敏颗粒）。

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).