Characterisation of the quinone-binding site of the plant alternative oxidase

酶是一种促进反应的蛋白质，使生物体能够获得生长、繁殖和维持所需的能量。在所有植物、一些真菌、酵母和锥虫（非洲昏睡病的罪魁祸首）中以及最近在动物中存在的一类重要酶是替代氧化酶。虽然替代氧化酶在所有这些生物体的呼吸中起着关键作用，但其确切的结构和功能仍不确定。除了在产热植物中产生热量的作用外，氧化酶的一般生理作用尚未得到最终确定。关于其结构，虽然目前没有晶体学数据，但普遍采用的观点是，该蛋白质插入线粒体内膜的一个小叶中，而替代氧化酶的活性位点包括一个非血红素二铁中心。本研究计划的总体目标是阐明替代氧化酶结构的分子性质，特别是底物结合位点。显然，这些基础知识具有相当大的工业相关性，因为它有可能极大地促进针对线粒体呼吸的植物病原杀菌剂和抗寄生虫药物的合理设计。从提出的研究中获得的结构和机制见解将进一步提高我们对植物（线粒体）能量代谢的基本理解。鉴于替代氧化酶活性对植物呼吸的浪费效应，这种增强的理解也可能具有潜在的未来农业生物技术意义。

Enzymes are proteins that facilitate the reactions that enable living organisms to acquire energy for growth, reproduction and maintenance. One significant class of enzymes that is present in all plants, some fungi, yeasts and trypansomes (responsible for African sleeping sickness) and more recently in animals are the alternative oxidases. Although the alternative oxidase plays a key role in respiration in all of these organisms its precise structure and function is still uncertain. Apart from it's role in the production of heat in thermogenic plant species, a general physiological role for the oxidase has, however, not been established conclusively. With respect to its structure, although no crystallographic data is currently available the generally adopted view is that the protein is inserted into one leaflet of the mitochondrial inner membrane and that the active-site of the alternative oxidase comprises a non-haem diiron centre. The overall objective of this research programme is to elucidate the molecular nature of the structure, specifically the substrate binding site, of the alternative oxidase. Clearly, such fundamental knowledge is of considerable industrial relevance, as it has the potential to greatly facilitate the rational design of phytopathogenic fungicides and anti-parasitic pharmaceuticals that are targeted at mitochondrial respiration. The structural and mechanistic insights that are gained from the proposed studies will furthermore improve our fundamental understanding of the (mitochondrial) energy metabolism of plants. Given the wasteful effect that alternative oxidase activity has on plant respiration, this enhanced understanding could also have potential future agro-biotechnological implications.