Complex I是呼吸鏈的第一種酶，它通過(guò)將NADH和苯醌之間的電子轉(zhuǎn)移同質(zhì)子轉(zhuǎn)位耦合起來(lái)，而在線粒體中的細(xì)胞能量生產(chǎn)中扮演一個(gè)中心角色,。這個(gè)巨大的復(fù)合物是呼吸鏈的最后環(huán)節(jié),，其機(jī)制和完整結(jié)構(gòu)過(guò)去并不為人們所知,。
現(xiàn)在,，來(lái)自大腸桿菌的Complex I的膜區(qū)域以及來(lái)自溫泉菌（嗜熱菌）的完整Complex I的結(jié)構(gòu)已被確定。這些結(jié)構(gòu)提供了關(guān)于耦合機(jī)制的有力線索：兩個(gè)主要區(qū)域界面上發(fā)生的構(gòu)形變化,，會(huì)驅(qū)動(dòng)一個(gè)長(zhǎng)阿爾法螺旋發(fā)生一種活塞式運(yùn)動(dòng),，使附近跨膜螺旋傾斜，導(dǎo)致質(zhì)子轉(zhuǎn)位,。本期封面圖片所描繪的是來(lái)自嵌入在類脂雙層中的溫泉菌（嗜熱菌）的呼吸鏈Complex I,。每個(gè)亞單元都用不同顏色表示，親水區(qū)域中的Fe-S簇顯示為球形,。背景所示為偏振光下的膜區(qū)域的晶體,。(生物谷Bioon.com)
ATP的生成、儲(chǔ)存和利用
呼 吸 鏈?
生物谷推薦原文出處：
Nature doi:10.1038/nature09066
The architecture of respiratory complex I
Rouslan G. Efremov 1, Rozbeh Baradaran 1 & Leonid A. Sazanov 1
1 Medical Research Council Mitochondrial Biology Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 0xY, UK
Complex I is the first enzyme of the respiratory chain and has a central role in cellular energy production, coupling electron transfer between NADH and quinone to proton translocation by an unknown mechanism. Dysfunction of complex I has been implicated in many human neurodegenerative diseases. We have determined the structure of its hydrophilic domain previously. Here, we report the α-helical structure of the membrane domain of complex I from Escherichia coli at 3.9?? resolution. The antiporter-like subunits NuoL/M/N each contain 14 conserved transmembrane (TM) helices. Two of them are discontinuous, as in some transporters. Unexpectedly, subunit NuoL also contains a 110-? long amphipathic α-helix, spanning almost the entire length of the domain. Furthermore, we have determined the structure of the entire complex I from Thermus thermophilus at 4.5?? resolution. The L-shaped assembly consists of the α-helical model for the membrane domain, with 63 TM helices, and the known structure of the hydrophilic domain. The architecture of the complex provides strong clues about the coupling mechanism: the conformational changes at the interface of the two main domains may drive the long amphipathic α-helix of NuoL in a piston-like motion, tilting nearby discontinuous TM helices, resulting in proton translocation.
