The physiological role, structure, and regulation of animal alternative oxidases

所有生物都使用电子传输系统(ETS)来产生生长和繁殖所需的能量。真核生物使用线粒体中的ETS来产生ATP，这些ETS的成分在将电子送入链中的络合物和将电子拉出的络合物方面差异很大。除了ETS中典型的末端氧化酶，细胞色素c氧化酶(COX)外，许多生物还含有第二末端氧化酶，称为交替氧化酶(AOX)。虽然AOX也利用氧作为最终的电子载体并产生水，但与COX不同的是，AOX不泵送质子，也不贡献用于产生ATP的质子动力和质子梯度。虽然乍一看，这种反应似乎是在浪费能量，但在许多生物体中，AOX的mRNA和蛋白质水平在环境压力期间会大大增加。这意味着AOX在成功适应应激条件中发挥了作用，可能是通过赋予ETS灵活性。

All organisms use electron transport systems (ETS) to generate energy for growth and reproduction. Eukaryotic organisms use ETS in mitochondria to produce ATP and the components of these ETS are highly variable in terms of the complexes that put electrons into the chain and the complexes that pull electrons out. In addition to the typical terminal oxidase in ETS, cytochrome c oxidase (COX), many organisms contain a second terminal oxidase called alternative oxidase (AOX). While AOX also utilizes oxygen as the final electron carrier and produces water, in contrast to COX, AOX does not pump protons and does not contribute to the proton motive force and proton gradient used to generate ATP. While at first glance this reaction appears to be energetically wasteful, AOX mRNA and protein levels greatly increase during environmental stress in many organisms. This implies that AOX plays a role in the successful acclimation to stress conditions, perhaps by conferring flexibility to the ETS.