Complex I is the largest and most intricate redox-driven proton pump of the respiratory chain. The structure of bacterial and mitochondrial complex I has been determined by X-ray crystallography and cryo-EM at increasing resolution. The recent cryo-EM structures of the complex I-like NDH complex and membrane bound hydrogenase open a new and more comprehensive perspective on the complex I superfamily. Functional studies and molecular modeling approaches have greatly advanced our understanding of the catalytic cycle of complex I. However, the molecular mechanism by which energy is extracted from the redox reaction and utilized to drive proton translocation is unresolved and a matter of ongoing debate. Here, we review progress in structure determination and functional characterization of complex I and discuss current mechanistic models.

中文翻译：

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呼吸系统综合体I-机械分析和结构确定方面的进展。

复合体I是呼吸链中最大，最复杂的氧化还原驱动质子泵。细菌和线粒体复合体I的结构已通过X射线晶体学和冷冻电磁法以增加的分辨率进行了测定。复杂的I类NDH复杂和膜结合的氢酶的最新冷冻肌电结构打开了一个新的和更全面的观点，对复杂我超家族。功能研究和分子建模方法极大地提高了我们对配合物I催化循环的理解。但是，从氧化还原反应中提取能量并用于驱动质子易位的分子机制尚未得到解决，并且仍在争论中。在这里，我们审查复杂I的结构确定和功能表征的进展，并讨论当前的力学模型。