生化上課課件生物氧化

1、Biological Oxidation1Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Preclinical Medicine School, SCU, 2006. 10第六章生物氧化Chapter 6. Biological OxidationBiological Oxidation2Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Preclinical Medicine School, SCU, 2006. 10Brief introduction

2、:5活細(xì)胞在執(zhí)行細(xì)胞功能時(shí)，隨時(shí)需要能量的補(bǔ)充，用于維持特定細(xì)胞結(jié)構(gòu)、合成細(xì)胞成分、產(chǎn)生電流及其它過(guò)程等。5在絕大多數(shù)生物體內(nèi)，能量的產(chǎn)生和儲(chǔ)存的最主要途徑是通過(guò)營(yíng)養(yǎng)分子（糖、脂和蛋白質(zhì)等）的徹底氧化（生成CO2和H2O）。在氧化的最終階段，伴隨 H 的氧化可將分解的大部分能量通過(guò)氧化磷酸化過(guò)程儲(chǔ)存到 ATP 分子中。Biological Oxidation3Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Preclinical Medicine School, SCU, 2006. 10Brief introduction

3、:5體內(nèi)大多數(shù)氧化反應(yīng)是以脫氫的形式發(fā)生的，在脫氫反應(yīng)中，1 個(gè)或 2 個(gè) H 原子(H+ + e)從底物脫下傳遞到氫接受體（主要是輔酶）。細(xì)胞內(nèi)的氧化-還原反應(yīng)涉及許多特異的電子傳遞體(electron carriers)。Biological Oxidation4Dr.Fucal Medicine School, SCU, 2006. 10Ø Catabolismof proteins,fats,andcarbohydrates in the three stagesof cellular respiration. Stage 1: oxidation of fatty acid

4、s, glucose, and some amino acids yields acetyl-CoA. Stage 2: oxidation of acetyl groups in thecitricacidcycleincludesfourstepsinwhichelectrons are abstracted. Stage 3: electrons carried by NADH and FADH2 are funneled into a chain of mitochondrial (or, in bacteria, plasma membrane bound) electron car

5、riersthe respiratory chain ultimately reducing O2 to H2O. This electron flow drives the production of ATP.Biological Oxidation5Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Preclinical Medicine School, SCU, 2006. 10Contents:6.1.16.1.26.1.36.1.4呼吸鏈氧化磷酸化氧化磷酸化的調(diào)節(jié)ATP 及其它“高能”化合物6.1.5 通過(guò)線粒體內(nèi)膜

6、的物質(zhì)轉(zhuǎn)運(yùn)6.1 生成 ATP 的氧化體系Oxidation System of ATP GenerationBiological Oxidation6Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Preclinical Medicine School, SCU, 2006. 10Contents:1. 什么是呼吸鏈 ?2. 呼吸鏈的組成3. 呼吸鏈的排列6.1.1 呼吸鏈Respiratory ChainBiological Oxidation7Dr.Fu Qiang. Dept.of Biochemistry &

7、; Molecular Biology, Preclinical Medicine School, SCU, 2006. 101. 呼吸鏈的概念l 是存在于線粒內(nèi)膜上的一系列蛋白、酶及輔助因子，它們組成相對(duì)獨(dú)立的復(fù)合物并按一定順序排列。營(yíng)養(yǎng)物質(zhì)氧化分解時(shí)產(chǎn)生的還原當(dāng)量(-H 和電子) 經(jīng)這些復(fù)合物一步步傳遞最終至 O2 生成 水，伴隨 H 的氧化過(guò)程還可產(chǎn)生大量的 ATP。6.1.1 呼吸鏈Respiratory ChainBiological Oxidation8Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Precli

8、nical Medicine School, SCU, 2006. 102. 呼吸鏈的組成l 線粒體上的呼吸鏈由一系列順序排列的電子傳遞體 (electron carriers) 所組成。這些電子傳遞體多數(shù)是線粒體內(nèi)膜上的整合蛋白(integral proteins),其輔基可以傳遞 1 個(gè)或 2 個(gè)電子。l 呼吸鏈上的電子傳遞體通常以膜嵌合(membrane-embedded) 的方式形成幾個(gè)相對(duì)獨(dú)立的巨分子復(fù)合物 (supramolecular complexes) ，它們可以通過(guò)某些物理方法進(jìn)行分離。Biological Oxidation9Dr.Fu Qiang. Dept.of Bi

9、ochemistry & Molecular Biology, Preclinical Medicine School, SCU, 2006. 10Ø 用去污劑(detergent) 溫和地處理線粒體內(nèi)膜后，可以得到 4 個(gè)單一的電子傳遞體復(fù)合物(electroncarrier complexes)，每個(gè)復(fù)合物分別可以在呼吸鏈中傳遞一部分電子。Biological Oxidation10Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Preclinical Medicine School, SCU, 200

10、6. 10l 間于復(fù)合體間的兩個(gè)游離成分: 泛醌和細(xì)胞色素cØ 復(fù)合體 I 和復(fù)合體 II 可分別將NADH 和琥珀酸(FADH2) 中的 H 和電子傳遞給泛醌(ubiquinone,或稱(chēng)輔酶Q, CoQ)。Ø 復(fù)合體III 將電子從還原型的泛醌(QH2) 傳遞給細(xì) 胞細(xì)胞 c (Cyt c)。Biological Oxidation11Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Preclinical Medicine School, SCU, 2006. 10Ø Summary of t

11、he flow of electrons and protons through the four complexes of the respiratory chain. Electrons reach Q through Complexes Iand II. QH2 serves as a mobile carrier of electrons and protons. It passes electrons to Complex III, which passes them to another mobile connecting link, cytochrome c. Complex I

12、V then transfers electrons from reduced cytochrome c to O2. Electron flow through Complexes I, III, and IV is accompanied by proton flow from the matrix to the intermembrane space. Recall that electrons from oxidation of fatty acids can also enter the respiratory chain through Q.Biological Oxidation

13、12Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Preclinical Medicine School, SCU, 2006. 10(1). 復(fù)合體 I:NADH-泛醌還原酶(或 NADH 脫氫酶)l 復(fù)合體 I 是一個(gè)大分子酶復(fù)合物，至少含有 42個(gè)多肽鏈，這其中包括 1 個(gè) 含 FMN 的黃素蛋白和至少 6 個(gè)鐵-硫中心(iron-sulfur centers), 或稱(chēng)鐵-硫簇(iron-sulfur clusters)。l 在復(fù)合體 I 中進(jìn)行的主要電子傳遞:NADH Æ FMN Æ Fe-S

14、Æ QBiological Oxidation13Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Preclinical Medicine School, SCU, 2006. 10Ø Electrons and protons transferring in NADH: ubiquinone oxidoreductase (Complex I).Biological Oxidation14Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology,

15、 Preclinical Medicine School, SCU, 2006. 10Ø Oxidoreduction of NAD and NADP.Nicotinamideadenine dinucleotide, NAD,and its phosphorylated analog NADP undergo reduction to NADH and NADPH, accepting ahydride ion (two electrons and one proton) from an oxidizable substrate. The hydride ion is added

16、to either the front (the A side) or the back (the B side) of the planar nicotinamide ring.Biological Oxidation15Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Preclinical Medicine School, SCU, 2006. 10Ø The transferring of protons and electrons via FMN.Flavoproteins containa very ti

17、ghtly, sometimes covalently, bound flavin nucleotide, either FMN or FAD. Theoxidized flavin nucleotide can accept either one electron (yielding the semiquinone form) or two (yielding FMNH2 or FADH2). Electron transfer occurs because the flavoprotein has a higher reduction potential than the compound

18、 oxidized.Biological Oxidation16Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Preclinical Medicine School, SCU, 2006. 10Ø Iron-sulfur centers. TheFe-Scentersofiron-sulfur proteins may be as simple as (a), with a single Fe ion surrounded bythe S atoms of four Cys residues. Other cen

19、ters include both inorganic and Cys S atoms, as in (b) 2Fe-2S or (c) 4Fe-4S centers. (d) The ferredoxin of the cyanobacterium Anabaena 7120 has one 2Fe- 2S center (PDB ID 1FRD); Fe is red, inorganic S2 is yellow, and the S of Cys is orange. (Note that in these designations only the inorganic S atoms

20、 are counted. For example, in the 2Fe-2S center (b), each Fe ion is actually surrounded by four S atoms.) The exact standard reduction potential of the iron in these centers depends on the type of center and its interaction with the associated protein.Biological Oxidation17Dr.Fu Qiang. Dept.of Bioch

21、emistry & Molecular Biology, Preclinical Medicine School, SCU, 2006. 10l Q 接受H 和電子后生醇(或稱(chēng)二氫泛醌, 即還原型的泛醌, QH2)，QH2 隨即可在線粒體內(nèi)膜上子傳遞給復(fù)合體 III，在這個(gè)的泵出。擴(kuò)散并進(jìn)一步將過(guò)程中會(huì)伴隨Biological Oxidation18Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Preclinical Medicine School, SCU, 2006. 10Ø Ubiquinone (

22、Q, or coenzyme Q). Completereduction of ubiquinone requires two electrons and two protons, and occurs in two steps through the semiquinone radical intermediate.Biological Oxidation19Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Preclinical Medicine School, SCU, 2006. 10l 復(fù)合體 I 催化兩個(gè)偶聯(lián)的反應(yīng)

23、同時(shí)進(jìn)行：c 轉(zhuǎn)移NADH中的H: 和 1 個(gè)基質(zhì)中的H+ 至泛醌，生成QH2（這是一個(gè)放能反應(yīng)）：NADH + H+ +Q´ NAD+ + QH2l d 轉(zhuǎn)移基質(zhì)中的 4 個(gè)至線粒體內(nèi)外膜間隙（吸能反應(yīng)）：4HN´ 4HP+P for the positive side of the inner membrane (the intermembrane space), N for the negative side (the matrix).Biological Oxidation20Dr.Fu Qiang. Dept.of Biochemistry & Molec

24、ular Biology, Preclinical Medicine School, SCU, 2006. 10l 因此，復(fù)合體 I是一個(gè)質(zhì)子泵(proton pump)，它利用電子傳遞反應(yīng)釋放的能量，定向地(vectorial)將質(zhì)子從線粒體基質(zhì)內(nèi)泵出。NADH + 5HN+Q ´ NAD+QH2 + 4HP+P for the positive side of the inner membrane (theintermembrane spacN for the negative side (the matrix).Biological Oxidation21Dr.Fu Qiang

25、. Dept.of Biochemistry & Molecular Biology, Preclinical Medicine School, SCU, 2006. 10Ø Electrons and protons transferring in NADH:ubiquinone oxido- reductase (Complex I). Complex I catalyzes the transfer of a hydride ion fromNADH to FMN, from which two electrons pass through a series of Fe

26、-S centers to the ironsulfur protein N-2 in the matrix arm of the complex. Electron transfer from N-2 to ubiquinone on the membrane arm forms QH2, which diffuses into the lipid bilayer. This electron transfer also drives the expulsion from the matrix of four protons per pair of electrons.Biological

27、Oxidation22Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Preclinical Medicine School, SCU, 2006. 10Biological Oxidation23Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Preclinical Medicine School, SCU, 2006. 10(2). 復(fù)合體 II: 琥珀酸-泛醌還原酶(或 琥珀酸脫氫酶)l 復(fù)合體 II 含 4 個(gè)蛋白亞基及 5 個(gè)輔基(兩類(lèi))。

28、16; 亞基A 和B 朝向基質(zhì)側(cè)，它們含有 3 個(gè) 2Fe-2S中心，結(jié)合 1 分子 FAD，以及 1 個(gè)底物(琥珀酸)結(jié)合位點(diǎn)。Ø 亞基 C 和 D 為膜整合蛋白，均含有 3 個(gè)跨膜螺旋，它們含有 1 個(gè) 血紅素分子 (heme b) 以及 1個(gè)泛醌結(jié)合位點(diǎn)。Biological Oxidation24Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Preclinical Medicine School, SCU, 2006. 10Structure of Complex II (succinate dehydr

29、ogenase) of E. coli. Theenzyme has two transmembrane subunits, C (green) and D (blue); the cytoplasmic extensions contain subunits B (orange) and A (purple). Just behind the FAD in subunit A (gold) is the binding site for succinate (occupied in this crystal structure by the inhibitor oxaloacetate, g

30、reen). Subunit B has three sets of Fe-S centers (yellow and red); ubiquinone (yellow) is bound to subunit C; and heme b (purple) is sandwiched between subunits C and D. A cardiolipin molecule is so tightly bound to subunit C that it shows up in the crystal structure (gray spacefilling).Electrons mov

31、e (blue arrows) from succinateto FAD, then through the three Fe-S centers to ubiquinone. The heme b is not on the main path of electron transfer but protects againstthe formation of reactive oxygen species (ROS) by electrons that go astray.¾Biological Oxidation25Dr.Fu Qiang. Dept.of Biochemistr

32、y & Molecular Biology, Preclinical Medicine School, SCU, 2006. 10l 在復(fù)合體 II 上的電子傳遞途徑是：首先從底物琥珀酸傳遞至FAD，生成FADH2，再經(jīng)過(guò)Fe-S 中心傳遞給CoQ，生成還原型CoQ (QH2)。Ø 注: 血紅素(heme b)在復(fù)合體II 上不參與電子傳遞。Biological Oxidation26Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Preclinical Medicine School, SCU, 2006

33、. 10Biological Oxidation27Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Preclinical Medicine School, SCU, 2006. 10n 線粒體內(nèi)的某些脫氫酶（如脂酰CoA 脫氫酶、3-磷酸甘油脫氫酶）催化的脫氫反應(yīng)可以直接將底物的電子傳遞至CoQ（盡管其輔酶都是FAD）， 而不需要經(jīng)過(guò)復(fù)合體 II。Biological Oxidation28Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Preclini

34、cal Medicine School, SCU, 2006. 10(3). 復(fù)合體 III: 泛醌-細(xì)胞色素c 還原酶(或 細(xì)胞色素bc1復(fù)合物)l 復(fù)合體 III 的作用是將電子從還原型泛醌(QH2)傳遞至細(xì)胞色素 c (Cyt c)。l 復(fù)合體 III 在傳遞電子的同時(shí)，會(huì)伴隨將質(zhì)子定向地從基質(zhì)轉(zhuǎn)移到線粒體外(內(nèi)外膜間隙)。l 復(fù)合體 III 上的氧化還原的凈反應(yīng)為:QH2 + 2cyt c(Fe3+) + 2H´ Q + 2cyt c (Fe2+) + 4H+2NPBiological Oxidation29Dr.Fu Qiang. Dept.of Biochemistry

35、& Molecular Biology, Preclinical Medicine School, SCU, 2006. 10l 復(fù)合體 III 由兩個(gè)相同單體組成二聚體(dimer)，每個(gè)單體由 11 個(gè)亞基構(gòu)成。l 復(fù)合體 III 上的 3 個(gè)核心亞基：Ø 細(xì)胞色素b 及其兩個(gè)血紅素輔基(bH 和 bL);Ø Riske 鐵-硫蛋其2Fe-2S中心；紅素輔基Ø 細(xì)胞色素c1Biological Oxidation30Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Preclinica

36、l Medicine School, SCU, 2006. 10Ø Structure of a Complex III monomer. The complex III is a dimer of identical monomers, each with 11 different subunits. The functional core is three subunits:cytochrome b (green) with its two hemes (bH and bL, light red); the Rieske iron-sulfur protein (purple)

37、with its 2Fe-2S centers (yellow); and cytochrome c1 (blue) with its heme (red).Biological Oxidation31Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Preclinical Medicine School, SCU, 2006. 10l 復(fù)合體 III 上的電子傳遞機(jī)制:Ø 泛醌循環(huán)(Q 循環(huán)) 提供了一個(gè)在雙電子遞體(CoQ)和單電子遞體(Cyt b, c1, c)之間的一個(gè)轉(zhuǎn)換(swith)。同時(shí)很好地解釋了復(fù)合

38、體 III 也是一個(gè) 質(zhì)子泵，每當(dāng)一對(duì)電子經(jīng)復(fù)合體 III 傳遞至Cyt c時(shí)，會(huì)伴隨 4 個(gè)質(zhì)子轉(zhuǎn)出線粒體。Ø 盡管在復(fù)合體 III 上的電子傳遞機(jī)制很復(fù)雜，但凈結(jié)果卻很簡(jiǎn)單，即QH2 重新氧化成Q，2 分子Cyt c 被還原(Fe3+ ´ Fe2+)。Biological Oxidation32Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Preclinical Medicine School, SCU, 2006. 10Ø The Q cycle. The path of electro

39、ns through Complex III is shown by blue arrows. On the P side of the membrane, two molecules of QH2 are oxidized to Q near the P side, releasing two protons per Q (four protons in all) into the intermembrane space. Each QH2 donates one electron (via the Rieske Fe-S center) to cytochrome c1, and one

40、electron (via cytochrome b) to a molecule of Q near the N side, reducing it in two steps to QH2. This reduction also uses two protons per Q, which are taken up from the matrix.Biological Oxidation33Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Preclinical Medicine School, SCU, 2006. 10B

41、iological Oxidation34Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Preclinical Medicine School, SCU, 2006. 10n 細(xì)胞色素 c (Cyt c) 是位于線粒體內(nèi)外膜間隙的一個(gè)可溶性蛋白。當(dāng)Cyt c 的血紅素從復(fù)合體 III上獲得 1 個(gè)電子后，它隨即移向復(fù)合 IV，并向后者傳遞電子。Biological Oxidation35Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Preclinica

42、l Medicine School, SCU, 2006. 10Ø Prosthetic groups of cytochromes. Each group consistsof four five-membered, nitrogen-containing rings in a cyclic structure called a porphyrin. The four nitrogen atoms are coordinated with a central Fe ion,either Fe2+ or Fe3+. Iron protoporphyrin IX is found in

43、 b-type cytochromes and in hemoglobin and myoglobin. Heme c is covalently bound to the protein of cytochrome c through thioether bonds to two Cys residues. Heme a, found in the a-type cytochromes, has a long isoprenoid tail attached to one of the five-membered rings. The conjugated double- bond syst

44、em (shaded pink) of the porphyrin ring accounts for the absorption of visible light by these hemes.Biological Oxidation36Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Preclinical Medicine School, SCU, 2006. 10(4). 復(fù)合體 IV: 細(xì)胞色素c 氧化酶l 復(fù)體 IV 的作用是將還原型的Cyt c (Fe2+) 的電子傳遞給分子氧(O2)，并生成水。l 復(fù)合體 I

45、V 是一個(gè)位于線粒體內(nèi)膜上的大分子酶復(fù)合物(含13 個(gè)亞基，Mr 204 kDa)。Ø 亞基 II 有一個(gè)雙核中心 (CuA)，含 2 個(gè)銅離子，它們與兩個(gè)Cys殘基結(jié)合，這與鐵硫蛋白的2Fe-2S 中心有些類(lèi)似。Biological Oxidation37Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Preclinical Medicine School, SCU, 2006. 10Ø 亞基 I2 個(gè)血紅素個(gè)銅離子(C(分別命名為a 和 a3)，。血紅素a3與CuB形成另以及另一個(gè)雙核中心， 它們接受

46、血紅素a 的電子并將其轉(zhuǎn)移給與a3結(jié)合的O2。Ø 亞基 III 不參與電子傳遞，但其對(duì)復(fù)合體 IV 的功能完整性是必不可少的，其功能尚未完全闡明。Biological Oxidation38Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Preclinical Medicine School, SCU, 2006. 10Ø Critical subunits of cytochrome oxidase (Complex IV). The bovine complex is shown here. (a)

47、The core of Complex IV, with three subunits. Subunit I (yellow) has two heme groups, a and a3 (red), and a copper ion, CuB (green sphere). Heme a3 and CuB form a binuclear Fe-Cu center. Subunit II (blue) contains two Cu ions (green spheres) complexed with the SH groups of two Cys residues in a binuc

48、lear center, CuA, that resembles the 2Fe-2S centers of iron-sulfur proteins. This binuclear center and the cytochrome cbinding site are located in a domain of subunit II that protrudes from the P side of the inner membrane (into the intermembrane space). Subunit III (green) seems to be essential for

49、 Complex IV function, but its role is not well understood. (b) The binuclear center of CuA. The Cu ions (green spheres) share electrons equally. When the center is reduced they have the formal charges Cu1+Cu1+; when oxidized, Cu1.5+Cu1.5+. Ligands around the Cu ions include two His (dark blue), two

50、Cys (yellow), an Asp (red), and Met (orange) residues.Biological Oxidation39Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Preclinical Medicine School, SCU, 2006. 10l 復(fù)合體 IV 上的電子傳遞方向是：Cyt c ´ CuAcenter ´ heme a ´ heme a3CuB center ´ O2.Biological Oxidation40Dr.Fu Qian

51、g. Dept.of Biochemistry & Molecular Biology, Preclinical Medicine School, SCU, 2006. 10l 每當(dāng) 4 個(gè)電子通過(guò)復(fù)合體 IV 傳遞時(shí)，該酶可消耗基質(zhì)內(nèi)(N側(cè))的 4 個(gè)H+ 用于生成水。同時(shí)，復(fù)合體IV 也可利用氧化還原的自由能將質(zhì)子泵出至間隙(P側(cè))，每傳遞 1 個(gè)電子泵出 1 個(gè)質(zhì)子。l 復(fù)合體 IV 上的總反應(yīng)為：4Cyt c(Fe2+) + 8HN+ O2 ´ 4cyt c(Fe) + 4HP+ 2H2O+3+Biological Oxidation41Dr.Fu Qiang. De

52、pt.of Biochemistry & Molecular Biology, Preclinical Medicine School, SCU, 2006. 10Ø PathofelectronsthroughComplex IV. Thethreeproteinscritical to electron flow are subunits I, II,andIII.Thelargergreenstructureincludes the other ten proteins in thecomplex.ElectrontransferthroughComplex IV be

53、gins when two molecules of reduced cytochrome c (top) each donate an electron to the binuclear center CuA. From here electrons pass throughheme a to the Fe-Cu center (cytochromea3 and CuB). Oxygen now binds to hemea3 and is reduced to its peroxy derivative(O22) by two electrons from the Fe-Cu2center

54、. Delivery of two more electronsfromcytochromec(makingfourelectrons in all) converts the O22 to two2molecules of water, with consumption of four “substrate” protons from the matrix. At the same time, four more protons are pumped from the matrix by an as yet unknown mechanism.Biological Oxidation42Dr

55、.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Preclinical Medicine School, SCU, 2006. 10Biological Oxidation43Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Preclinical Medicine School, SCU, 2006. 103. 呼吸鏈組分的排列順序l 在呼吸鏈催化的整個(gè)反應(yīng)中，電子從 NADH，琥珀酸或其它底物經(jīng)黃素蛋白、泛醌、鐵-硫蛋白、細(xì)胞色素c，最后傳至O2。l 呼吸鏈

56、各組分排列順序的確定使用了多種方法:Ø 標(biāo)準(zhǔn)還原電位(E°) ：先對(duì)各電子傳遞體的標(biāo)準(zhǔn)還原電位進(jìn)行測(cè)定，再按由低到高的順序排列(因?yàn)殡娮涌偸莾A向自發(fā)地從低電位向高電位移動(dòng))。Biological Oxidation44Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Preclinical Medicine School, SCU, 2006. 10Ø 按氧化還原電遞鏈排列應(yīng)為:低到高的順序推導(dǎo)的電子傳Cyt b Cyt c1 Cyt c Cyt a NADH QCyt a3 O2Biological Oxidation45Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Preclinical Medicine School, SCU, 2006. 10Biological Oxidation46Dr.Fu Qiang. Dept.of Biochemistry & Molecular Biology, Pr