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Oxidoreductases, cytochromes

Figure 18.15. Structure of Q-Cytochrome C Oxidoreductase (Cytochrome BC j). This enzyme is a homodimer with "jljfo, 11 distinct polypeptide chains. The major prosthetic groups, three hemes and a 2Fe-2S cluster, mediate the electron-transfer reactions between quinones in the membrane and cytochrome c in the intermembrane space. Figure 18.15. Structure of Q-Cytochrome C Oxidoreductase (Cytochrome BC j). This enzyme is a homodimer with "jljfo, 11 distinct polypeptide chains. The major prosthetic groups, three hemes and a 2Fe-2S cluster, mediate the electron-transfer reactions between quinones in the membrane and cytochrome c in the intermembrane space.
Q-cytochrome c oxidoreductase (cytochrome hc ) Figure 18.11 Cytochrome c oxidase Figure 18.13... [Pg.1131]

Besides heme P-460 of hydroxylamine oxidoreductase, cytochrome P-460 has been isolated from N. europaea (Erickson and Hooper, 1972 Miller et al., 1984 Numata et al., 1990). Cytochrome P-460 shows a weak activity of hydroxylamine oxidoreductase, and its molecule is composed of 3 subunits of 18 kDa. As the amino acid sequence of the cytochrome differs from that of hydroxylamine oxidoreductase and DNA encoding the cytochrome is found to be different from that of the oxidoreductase, the cytochrome is not a proteolytic fragment of the oxidoreductase (Bergman and Hooper, 1994b). Indeed, cytochrome P-460 has recently been crystallized and its spatial structure has been determined (Pearson et al., 2007). Its heme is a modified heme C in which lysine residue links to... [Pg.21]

In the enzymatic oxidation of hydroxylamine catalyzed by hydroxylamine oxidoreductase, the electron acceptor for the oxidoreductase, cytochrome c-554, should be kept in the oxidized form as much as possible to accept electrons rapidly from hydroxylamine and NOH. For this purpose, sufficient air should be supplied for the bacteria to oxidize ammonia efficiently. If the air supply is not enough to oxidize hydroxylamine to nitrite, nitrous oxide (N20) occurs during the bacterial oxidation of ammonia (Poth, 1986 Anderson et al., 1993). Probably... [Pg.23]

The ubiquinol-cytochrome c oxidoreductase (cytochrome bc complex) of Rhodobacter sphaeroides is an integral component of the intracytoplasmic membrane (ICM) and functions in light-driven cyclic electron flow and the conservation of radiant energy as an electrochemical proton gradient. Previous studies on the assembly of electron transfer constituents in/ , sphaeroides have demonstrated that complete cycles of electron flow do not occur merely upon insertion of newly synthesized reaction centers at sites of initiation of ICM growth, but instead, subsequent synthesis and assembly of redox centers of the be complex are required [1]. To further characterize the assembly process and for detailed structural investigations, the complex was purified and antibodies were raised against the isolated polypeptide constituents. In this report, results on the localization and levels of the feCj complex in various membrane fractions are presented a detailed description of the structurd work will appear elsewhere [2]. [Pg.2155]

Electron Transport Between Photosystem I and Photosystem II Inhibitors. The interaction between PSI and PSII reaction centers (Fig. 1) depends on the thermodynamically favored transfer of electrons from low redox potential carriers to carriers of higher redox potential. This process serves to communicate reducing equivalents between the two photosystem complexes. Photosynthetic and respiratory membranes of both eukaryotes and prokaryotes contain stmctures that serve to oxidize low potential quinols while reducing high potential metaHoproteins (40). In plant thylakoid membranes, this complex is usually referred to as the cytochrome b /f complex, or plastoquinolplastocyanin oxidoreductase, which oxidizes plastoquinol reduced in PSII and reduces plastocyanin oxidized in PSI (25,41). Some diphenyl ethers, eg, 2,4-dinitrophenyl 2 -iodo-3 -methyl-4 -nitro-6 -isopropylphenyl ether [69311-70-2] (DNP-INT), and the quinone analogues,... [Pg.40]

L-lactate-cytochrome c-oxidoreductase (flavocytochrome was isolated for the first time from the thermo-tolerant yeast H. polymorpha. The mentioned above enzyme preparations were used for construction of the biorecognition elements of electrochemical sensors. [Pg.347]

Another pathway is the L-glycerol 3-phosphate shuttle (Figure 11). Cytosolic dihydroxyacetone phosphate is reduced by NADFl to s.n-glycerol 3-phosphate, catalyzed by s,n-glycerol 3-phosphate dehydrogenase, and this is then oxidized by s,n-glycerol 3-phosphate ubiquinone oxidoreductase to dihydroxyacetone phosphate, which is a flavoprotein on the outer surface of the inner membrane. By this route electrons enter the respiratory chain.from cytosolic NADH at the level of complex III. Less well defined is the possibility that cytosolic NADH is oxidized by cytochrome bs reductase in the outer mitochondrial membrane and that electrons are transferred via cytochrome b5 in the endoplasmic reticulum to the respiratory chain at the level of cytochrome c (Fischer et al., 1985). [Pg.133]

Moreover, an electron transfer chain could be reconstituted in vitro that is able to oxidize aldehydes to carboxylic acids with concomitant reduction of protons and net production of dihydrogen (213, 243). The first enzyme in this chain is an aldehyde oxidoreductase (AOR), a homodimer (100 kDa) containing one Mo cofactor (MOD) and two [2Fe—2S] centers per subunit (199). The enzyme catalytic cycle can be regenerated by transferring electrons to flavodoxin, an FMN-con-taining protein of 16 kDa (and afterwards to a multiheme cytochrome and then to hydrogenase) ... [Pg.409]

The condition known as fatal infantile mitochondrial myopathy and renal dysfunction involves severe diminution or absence of most oxidoreductases of the respiratory chain. MELAS (mitochondrial encephalopathy, lactic acidosis, and stroke) is an inherited condition due to NADHiubiquinone oxidoreductase (complex I) or cytochrome oxidase deficiency. It is caused by a muta-... [Pg.100]

The subcellular location of PG was studied in cells disrupted by osmotic lysis through formation and disruption of sphaeroplasts from self-induced anaerobically-grown cells. A discontinuous sucrose-density gradient produced four bands labelled I, II, III and IV. Band I included many vesicles and a peak of alkaline phosphatase activity (a vacuolar marker in yeasts), NADPH cytochrome c oxidoreductase activity, an endoplasmic reticulum marker, and... [Pg.864]

The catalytic activity of CYP enzymes requires functional coupling with its redox partners, cytochrome P450 NADPH oxidoreductase (OR) and cytochrome bs. Measurable levels of these two proteins are natively expressed in most cell lines. Therefore, introduction of only the CYP cDNA is generally needed for detectable catalytic activity. However, the levels of expression of the redox partner proteins may not support maximal CYP catalytic activity, and therefore enhancement of OR levels may be desirable. This approach has been used successfully with an adenovirus expression system in LLC-PKi cells [12],... [Pg.333]

Gardner et al. [165] have shown that the redox-cycling agent phenazine methosulfate (PMS), mitochondrial ubiquinol-cytochrome c oxidoreductase, or hypoxia inactivated aco-nitase in mammalian cells. It has been proposed that the inactivation of aconitase is mediated by superoxide produced by prooxidants because the overproduction of mitochondrial MnSOD protected aconitase from inactivation by the prooxidants mentioned above except hyperoxia. Later on, the reaction of superoxide with aconitases began to be considered as one of the most important ways to NTBI generation in vivo. [Pg.708]

Complex III (CoQ cytochrome c oxidoreductase) transfers electrons from CoQ to cytochrome c, through a sequence of cytochrome and iron-sulfur cofactors. Here, Alf for the couple CoQ/cytochrome c is 0.19 V, corresponding to a AG° of —36.7 kJ/mol, again enough to power the synthesis of an ATP molecule and to ensure that protons are pumped across the inner mitochondrial membrane. [Pg.99]


See other pages where Oxidoreductases, cytochromes is mentioned: [Pg.343]    [Pg.167]    [Pg.189]    [Pg.171]    [Pg.405]    [Pg.72]    [Pg.263]    [Pg.67]    [Pg.263]    [Pg.22]    [Pg.34]    [Pg.70]    [Pg.82]    [Pg.152]    [Pg.315]    [Pg.343]    [Pg.167]    [Pg.189]    [Pg.171]    [Pg.405]    [Pg.72]    [Pg.263]    [Pg.67]    [Pg.263]    [Pg.22]    [Pg.34]    [Pg.70]    [Pg.82]    [Pg.152]    [Pg.315]    [Pg.719]    [Pg.722]    [Pg.722]    [Pg.358]    [Pg.127]    [Pg.7]    [Pg.10]    [Pg.322]    [Pg.425]    [Pg.329]    [Pg.351]    [Pg.961]    [Pg.719]    [Pg.569]    [Pg.610]    [Pg.151]    [Pg.37]    [Pg.214]   
See also in sourсe #XX -- [ Pg.333 , Pg.450 ]




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CoQ-cytochrome c oxidoreductase

Cytochrome P450 oxidoreductase

Cytochrome P450 oxidoreductase (POR

Cytochrome dependent oxidoreductases

Fe(II)-Cytochrome c Oxidoreductase

Oxidoreductase

Sulfite cytochrome c oxidoreductase

The ubiquinol-cytochrome c oxidoreductase of photosynthetic bacteria

Ubiquinol: cytochrome c oxidoreductase

Ubiquinone-cytochrome c oxidoreductase

Ubiquinone:cytochrome oxidoreductase

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