Copper active sites in biology.
Copper active sites in biology.
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DOI：
10.1021/cr400327t
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发表时间：
2014-04-09
期刊：
影响因子：
62.1
通讯作者：
Tian, Li
中科院分区：
文献类型：
--
作者：
Solomon, Edward I.;Heppner, David E.;Johnston, Esther M.;Ginsbach, Jake W.;Cirera, Jordi;Qayyum, Munzarin;Kieber-Emmons, Matthew T.;Kjaergaard, Christian H.;Hadt, Ryan G.;Tian, Li
基于其普遍可及的I/II氧化还原偶和生物利用度，铜在自然界中发挥着广泛的作用，主要涉及电子转移（ET）、o2结合、活化和还原、NO 2和n2o还原以及底物活化。执行ET的铜位点是具有高共价Cu (II) -S （Cys）键的单核蓝色Cu位点和具有具有Cu - Cu键的Cu 2 (S (Cys)) 2核的双核Cu a位点，该Cu 2 (S)) 2核心具有Cu - Cu键，使该位点（Cu(1.5) 2）保持氧化状态。与无机铜配合物相比，这些金属蛋白位点经常在长距离上快速转移电子，正如之前所述。（1-4）这里只考虑蓝Cu和Cu A位点与多中心酶分子内ET的关系。本文的重点是图1中的Cu酶。许多参与o2活化和还原，其中大多数被认为涉及至少两个电子来克服自旋禁止性和单电子还原成超氧化物的低电位（图2）。（5,6）由于Cu （III）氧化还原状态尚未在生物学中观察到，这需要多个Cu中心或一个铜和一个额外的氧化还原活性有机辅因子。后者是在残基（Tyr）的生物发生反应中形成的，该反应也在蛋白质的第一次周转中被Cu催化。然而，最近有一些酶被建议利用一个Cu通过单电子还原来激活O 2，形成Cu (II) -O 2•-中间体（球内氧化还原过程），了解驱动该反应的活性位点要求是很重要的。催化o2四电子还原为h2o的氧化酶是独一无二的，因为它们在一步中有效地完成了这个反应，这表明第一个两电子步骤的过氧化产物的第二个两电子还原的自由能垒非常低。在自然界中，这需要一个三核铜簇（在多铜氧化酶中）或一个铜/铁/血红素铁簇（在细胞色素氧化酶中）。前者几乎没有过电位，最大限度地提高了其氧化底物的能力和在生物燃料电池中的应用，而后一类酶利用多余的能量来泵送质子用于ATP合成。在细菌反硝化过程中，单核Cu中心催化亚硝酸盐的单电子还原为NO，而独特的μ 4硫化物桥接四核铜簇催化n2 - O还原为n2和h2o，这是一个双电子过程，但需要四个铜原子。最后，现在有几种酶利用氧化的Cu （II）中心激活共价结合的底物与o2反应。
On the basis of its generally accessible I/II redox couple and bioavailability, copper plays a wide variety of roles in nature that mostly involve electron transfer (ET), O 2 binding, activation, and reduction, NO 2–and N 2 O reduction, and substrate activation. Copper sites that perform ET are the mononuclear blue Cu site that has a highly covalent Cu (II)–S (Cys) bond and the binuclear Cu A site that has a Cu 2 (S (Cys)) 2 core with a Cu–Cu bond that keeps the site delocalized (Cu (1.5) 2) in its oxidized state. In contrast to inorganic Cu complexes, these metalloprotein sites transfer electrons rapidly often over long distances, as has been previously reviewed.(1-4) Blue Cu and Cu A sites will only be considered here in their relation to intramolecular ET in multicenter enzymes. The focus of this review is on the Cu enzymes in Figure 1. Many are involved in O 2 activation and reduction, which have mostly been thought to involve at least two electrons to overcome spin-forbidden-ness and the low potential of the one-electron reduction to superoxide (Figure 2).(5, 6) Since the Cu (III) redox state has not been observed in biology, this requires either more than one Cu center or one copper and an additional redox-active organic cofactor. The latter is formed in a biogenesis reaction of a residue (Tyr) that is also Cu catalyzed in the first turnover of the protein. Recently, however, there have been a number of enzymes suggested to utilize one Cu to activate O 2 by one-electron reduction to form a Cu (II)–O 2•–intermediate (an inner-sphere redox process), and it is important to understand the active site requirements to drive this reaction. The oxidases that catalyze the four-electron reduction of O 2 to H 2 O are unique in that they effectively perform this reaction in one step, indicating that the free energy barrier for the second two-electron reduction of the peroxide product of the first two-electron step is very low. In nature, this requires either a trinuclear Cu cluster (in the multicopper oxidases) or a Cu/Tyr/heme Fe cluster (in the cytochrome oxidases). The former accomplishes this with almost no overpotential, maximizing its ability to oxidize substrates and its utility in biofuel cells, while the latter class of enzymes use the excess energy to pump protons for ATP synthesis. In bacterial denitrification, a mononuclear Cu center catalyzes the one-electron reduction of nitrite to NO while a unique μ 4 sulfide bridged tetranuclear copper cluster catalyzes the reduction of N 2 O to N 2 and H 2 O, a two-electron process yet requiring four copper atoms. Finally, there are now several classes of enzymes that utilize an oxidized Cu (II) center to activate a covalently bound substrate to react with O 2.
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影响因子：
2.9
作者：
Adelroth, P;Gennis, RB;Brzezinski, P
通讯作者：
Brzezinski, P
影响因子：
8
作者：
Airenne, TT;Nymalm, Y;Salminen, TA
通讯作者：
Salminen, TA
DOI：
10.1111/j.1432-1033.1975.tb04102.x
发表时间：
1975-01-01
期刊：
EUROPEAN JOURNAL OF BIOCHEMISTRY
影响因子：
--
作者：
ANDREASSON, LE
通讯作者：
ANDREASSON, LE
影响因子：
4.8
作者：
ADMAN, ET;GODDEN, JW;TURLEY, S
通讯作者：
TURLEY, S
影响因子：
3.5
作者：
AASA, R;BRANDEN, R;VANNGARD, T
通讯作者：
VANNGARD, T