Resonance Raman evidence for low-spin Fe2+ heme a3 in energized cytochrome c oxidase: implications for the inhibition of O2 reduction.
Resonance Raman evidence for low-spin Fe2+ heme a3 in energized cytochrome c oxidase: implications for the inhibition of O2 reduction.
复制标题
通电细胞色素 c 氧化酶中低自旋 Fe2 血红素 a3 的共振拉曼证据：对抑制 O2 还原的影响。
DOI：
10.1021/bi00465a009
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发表时间：
1990
期刊：
影响因子：
2.9
通讯作者：
Spiro,TG
中科院分区：
文献类型：
--
作者：
Ray,GB;Copeland,RA;Lee,CP;Spiro,TG
1989年12月6日收到的修订手稿摘要：报道了在441.6 nm处被激发的还原的亚线粒体颗粒的共振拉曼光谱，其中细胞色素C氧化酶血红素a基团的拉曼光谱被选择性地增强。加入ATP使膜通电，在1644 cm~(-1)处形成新的带，在1567 cm~(-1)处的带部分失去强度。这些变化是通过在还原的细胞色素c氧化酶中加入氰化物来模拟的，并归因于细胞色素(Cyt)<；Z3从高自旋状态到低自旋状态的部分转化。这种转化可通过加入过量的寡霉素(一种ATPase抑制剂)或FCCP(质子转运的解偶联剂)来取消，并在消耗ATP时逆转。观察到的自旋态转换归因于内源配体与CytA3Fe原子的结合。这种连接被认为是由局部pH升高和/或与产生跨膜电位相关的整体构象变化所诱导的。由于02结合需要在细胞色素A3处有一个空位的配位位点，因此该位点的连接必须延缓02的还原，从而为呼吸作用的能量连锁调节提供了一种简单的机制。在还原的细胞色素C氧化酶中加入Ca~(2+)或H~+后，RR谱无明显变化。与膜能化相关的细胞色素A3自旋状态的改变与细胞色素C氧化酶(Cyt ox.)是自然界的主要能量转换器之一(Wikstrom等人，1981)。这种多亚单位蛋白质穿过线粒体内膜，接受来自胞质蛋白细胞色素(Cyt)c的四个电子，并将它们转移到膜的基质侧，在那里它们被用来将O2还原为水。02还原反应每个传递给基质的电子消耗一个质子；该反应产生的氧化还原自由能用于将额外的质子从基质泵入胞浆。由此产生的跨膜质子电化学势(µ+)驱动ATP水解质子泵(F^oATPase)向后，从ADP和PI合成ATP(Nicholls，1982)。
Revised Manuscript Received December 6, 1989 abstract: Resonance Raman (RR) spectra are reported for reduced submitochondrial particles (SMP) with excitationat 441.6 nm, where Raman bands of the cytochrome c oxidase heme a groups are selectively enhanced. Addition of ATP to energize the membranes induces the formation of a new band at 1644 cm'1 and partial loss of intensity in a band at 1567 cm'1. These changes are modeled by adding cyanide to reduced cytochrome c oxidase and are attributed to partial conversion of cytochrome (cyt)< z3 from a high-spin to a low-spin state. This conversion is abolished by addition of excess oligomycin, an ATPase inhibitor, or FCCP, an uncoupler of proton translocation, and is reversed when the ATP is consumed. The observed spin-state conversion is attributed tothe binding of an endogenous ligand to the cyt a3 Fe atom. This ligation is suggested to be induced by a local increase in pH and/or by a global conformation changeassociated with the generation of a transmembrane potential. Since 02 binding requires a vacant coordination site at cyt a3, the ligation of this site must retard 02 reduction and could thus provide a simple mechanism for energy-linked regulation of respiration. No changes in the RR spectrum were observed upon adding Ca2+ or H+ to reduced cytochrome c oxidase. The cyt a3 spin-state change associated with membraneenergization is unrelated to the cyt a absorption red shift induced by adding Ca2+ or H+ to cytochrome c oxidase.(cytochrome c oxidase (cyt ox.) is one of nature’s primary energy transducers (Wikstrom et al., 1981). This multisubunit protein traverses the inner mitochondrial membrane, accepting four electrons from the cytosolic protein cytochrome (cyt) c and transferring them to the matrix side of the membrane, where they are used to reduce 02 to water. The 02 reduction reaction consumes one proton per electron delivered to the matrix; the redox free energy generated by this reaction is used to pump an additional proton from the matrix to the cytosol. The resulting proton electrochemical potential (µ+) across the membrane drives the ATP-hydrolyzing proton pump (F^ oATPase) backward, synthesizing ATP from ADP and Pi (Nicholls, 1982).