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1.
Cytochrome c and cytochrome b5 form an electrostatically associated electron transfer complex. Computer models of this and related complexes that were generated by docking the x-ray structures of the individual proteins have provided insight into the specificity and mechanism of electron transfer reactions. Previous static modeling studies were extended by molecular dynamics simulations of a cytochrome c-cytochrome b5 intermolecular complex. The simulations indicate that electrostatic interactions at the molecular interface results in a flexible association complex that samples alternative interheme geometries and molecular conformations. Many of these transient geometries appear to be more favorable for electron transfer than those formed in the initial model complex. Of particular interest is a conformational change that occurred in phenylalanine 82 of cytochrome c that allowed the phenyl side chain to bridge the two cytochrome heme groups. 相似文献
2.
Probing the mechanisms of macromolecular recognition: the cytochrome b5-cytochrome c complex 总被引：3，自引：0，他引：3
The specificity of complex formation between cytochrome b5 (cyt b5) and cytochrome c (cyt c) is believed to involve the formation of salt linkages between specific carboxylic acid residues of cyt b5 with lysine residues on cyt c. Site-directed mutagenesis was used to alter the specified acidic residues of cyt b5 to the corresponding amide analogues, which resulted in a lower affinity for complex formation with cyt c. The dissociation of the complex under high pressure resulted in specific volume changes, the magnitude of which reflected the degree of solvation of the acidic residues in the proposed protein-protein interface. 相似文献
3.
N Liang A G Mauk G J Pielak J A Johnson M Smith B M Hoffman 《Science (New York, N.Y.)》1988,240(4850):311-313
Yeast iso-1-cytochrome c (Cc) mutants have been constructed with Phe, Tyr, Gly, Ser, Leu, and Ile at position 82, each with Thr substituted for Cys at position 102. Their long-range electron transfer with zinc-substituted cytochrome c peroxidase (ZnCcP) has been studied by two kinetic techniques. The charge-separated complex, [(ZnCcP)+,FeIICc] converts to [ZnCcP,FeIIICc] by a single, intracomplex electron transfer step that is not governed by "gating" through possible rapid dissociation of the complex or isomerization (for example, heme-ligand) by FeIICc subsequent to its formation from FeIIICc. In every variant with an aliphatic residue at position 82 of Cc, the rate of this electron transfer process is approximately 10(4) slower at approximately 0 degrees C than for the two variants with aromatic residues. 相似文献
4.
Identification by ENDOR of Trp191 as the free-radical site in cytochrome c peroxidase compound ES 总被引：8，自引：0，他引：8
The chemical identity of the amino acid free-radical site that represents one of the two oxidizing equivalents stored in the H2O2-oxidized intermediate (compound ES) of the mitochondrial heme enzyme, cytochrome c peroxidase (CcP) has been sought for almost a quarter of a century. Site-directed mutagenesis alone cannot yield this answer. Low-temperature 35-gigahertz (Q-band) electron nuclear double resonance (ENDOR) spectroscopy was used to examine compound ES prepared from proteins containing specifically deuterated methionine or tryptophan, as well as the amino acid replacement Trp51----Phe. The results definitely identify the site of the radical in compound ES as tryptophan, most likely Trp191. 相似文献
5.
Phosphorylation coupled to the transfer of electrons from glutathione to cytochrome c 总被引：1，自引：0，他引：1
Formation of adenosine diphosphate from adenosine monophosphate and inorganic phosphate can be coupled to the oxidation of reduced glutathione by cytochrome c in a reaction which requires oxidized glutathione as a catalyst. The reaction occurs with purified materials in tris(hydroxymethyl)aminomethane buffer and may represent the type reaction for one or more oxidative phosphorylations. 相似文献
6.
Antibodies to rabbit cytochrome c arising in rabbits 总被引：3，自引：0，他引：3
Antibodies reactive with rabbit cytochrome c have been observed in rabbits immunized with several heterologous cytochromes. Such antibodies have also been observed in rabbits immunized with rabbit cytochrome c conjugated to bovine gamma globulin. The serum of a rabbit immunized with human cyto chrome c reacted with the cytochrome c of the same rabbit. 相似文献
7.
The basic proteins protamine (sulfate), histone, lysozyme, and ribonuclease were found to be potent inhibitors of mammalian heart muscle cytochromec oxidase. Their inhibitions were completely reversed in the presence of a strongly anionic polyglucose sulfate. With fresh rat heart muscle homogenates, Keili and Hartree type of beef heart muscle particulates, and deoxycholate-solubilized oxidase preparations, the reversible nature of the phenomenon was demonstrated with manometric and spectrophotometric assays for cytochrome c oxidase. 相似文献
8.
NMR characterization of surface interactions in the cytochrome b5-cytochrome c complex 总被引：2，自引：0，他引：2
A M Burch S E Rigby W D Funk R T MacGillivray M R Mauk A G Mauk G R Moore 《Science (New York, N.Y.)》1990,247(4944):831-833
The complex formed in solution by native and chemically modified cytochrome c with cytochrome b5 has been studied by 1H and 13C nuclear magnetic resonance spectroscopy (NMR). Contrary to predictions of recent theoretical analysis, 1H NMR spectroscopy indicates that there is no major movement of cytochrome c residue Phe82 on binding to cytochrome b5. The greater resolution provided by 13C NMR spectroscopy permits detection of small perturbations in the environments of cytochrome c residues Ile75 and Ile85 on binding with cytochrome b5, a result that is in agreement with earlier model-building experiments. As individual cytochrome c lysyl residues are resolved in the 1H NMR spectrum of N-acetimidylated cytochrome c, the interaction of this modified protein with cytochrome b5 has been studied to evaluate the number of cytochrome c lysyl residues involved in binding to cytochrome b5. The results of this experiment indicate that at least six lysyl residues are involved, two more than predicted by static model building, which indicates that cytochrome c and cytochrome b5 form two or more structurally similar 1:1 complexes in solution. 相似文献
9.
Effect of Azoxystrobin on Oxygen Consumption and cyt b Gene Expression of Colletotrichum capsici from Chilli Fruits 总被引：1，自引：1，他引：0
Azoxystrobin acts as an inhibitor of electron transport by binding to the Qo center of cytochrome b （cyt b）. Resistance to azoxystrobin was usually caused by the point mutation of cyt b gene or by the induction of alternative respiration. Oxygen consumption test for mycelia of Colletotrichum capsici showed that azoxystrobin inhibited mycelial respiration within 12 h; however, as time went on, the respiration of the mycelia recovered when the mycelia were treated with azoxystrobin and salicylhydroxamic acid （SHAM, a known inhibitor of alternative respiration）, and the oxygen consumption of the mycelia could not be inhibited. Meanwhile, cytochrome b （cyt b） gene expression increased with the recovery of mycelial respiration. The increased cyt b gene expression might play a role in the development of resistance to azoxystrobin in C. capsici. 相似文献
10.
Collman JP Devaraj NK Decréau RA Yang Y Yan YL Ebina W Eberspacher TA Chidsey CE 《Science (New York, N.Y.)》2007,315(5818):1565-1568
We studied the selectivity of a functional model of cytochrome c oxidase's active site that mimics the coordination environment and relative locations of Fe(a3), Cu(B), and Tyr(244). To control electron flux, we covalently attached this model and analogs lacking copper and phenol onto self-assembled monolayer-coated gold electrodes. When the electron transfer rate was made rate limiting, both copper and phenol were required to enhance selective reduction of oxygen to water. This finding supports the hypothesis that, during steady-state turnover, the primary role of these redox centers is to rapidly provide all the electrons needed to reduce oxygen by four electrons, thus preventing the release of toxic partially reduced oxygen species. 相似文献
11.
Two morphologically distinct blood-brain barriers preventing entry of cytochrome c into cerebrospinal fluid 总被引：1，自引：0，他引：1
After intravenous injection, cytochrome c does not enter the cerebrospinal fluid. In most areas of the brain, the marker is prevented from leaving cerebral vessels by the capillary endothelium. In the choroid plexus, the marker passes freely out of capillaries into the extracellular space. However, it does not traverse tight junctions between epithelial cells and is rapidly incorporated into mnembrane-bound vesicles within the cell cytoplasm. Thereafter, cytochrome c is apparently removed by lysosomal degradation. These data suggest that there are at least two morphologically distinct blood-brain barriers to cytochrome c and that pinocytosis may be a mechanism for intracellular degradation rather than transcellular transport. 相似文献
12.
Roszak AW Howard TD Southall J Gardiner AT Law CJ Isaacs NW Cogdell RJ 《Science (New York, N.Y.)》2003,302(5652):1969-1972
The crystal structure at 4.8 angstrom resolution of the reaction center-light harvesting 1 (RC-LH1) core complex from Rhodopseudomonas palustris shows the reaction center surrounded by an oval LH1 complex that consists of 15 pairs of transmembrane helical alpha- and beta-apoproteins and their coordinated bacteriochlorophylls. Complete closure of the RC by the LH1 is prevented by a single transmembrane helix, out of register with the array of inner LH1 alpha-apoproteins. This break, located next to the binding site in the reaction center for the secondary electron acceptor ubiquinone (UQB), may provide a portal through which UQB can transfer electrons to cytochrome b/c1. 相似文献
13.
Digestion of a preparation of cytochromes b and c(1) with pancreatic protease followed by ammonium sulfate precipitation resulted in a soluble cytochrome b uncontaminated by cytochrome C(l). This preparation, which was free of succinic dehydrogenase and cytochrome oxidase activity, had an estimated deltaE(1 cm)(1g/ml) of 102 for its alpha-peak. In the reduced form absorption maxima were found at 560 to 562, 530 to 532, and 427 to 428 mmicro, and in the oxidized form, at 413 mmicro. 相似文献
14.
The cytochrome b6f complex provides the electronic connection between the photosystem I and photosystem II reaction centers of oxygenic photosynthesis and generates a transmembrane electrochemical proton gradient for adenosine triphosphate synthesis. A 3.0 angstrom crystal structure of the dimeric b6f complex from the thermophilic cyanobacterium Mastigocladus laminosus reveals a large quinone exchange cavity, stabilized by lipid, in which plastoquinone, a quinone-analog inhibitor, and a novel heme are bound. The core of the b6f complex is similar to the analogous respiratory cytochrome bc1 complex, but the domain arrangement outside the core and the complement of prosthetic groups are strikingly different. The motion of the Rieske iron-sulfur protein extrinsic domain, essential for electron transfer, must also be different in the b6f complex. 相似文献
15.
为探讨线粒体能量代谢中细胞色素c氧化酶(cytochromecoxidase,CcO)在布氏田鼠(Microtusbrandti)生长发育过程中的作用,应用紫外分光光度法测定了不同日龄的幼鼠肝脏内线粒体蛋白含量及CcO活性。结果发现根据幼鼠肝脏内线粒体蛋白的含量可将生长发育大致分为3个阶段:1～3日龄,4～19日龄,20日龄至成体。CcO活性变化趋势则呈倒钟形,以17日龄的CcO活性为最高。据此推测布氏田鼠肝脏内CcO的活性可能与恒温机制的建立有关系。 相似文献
16.
Summers ZM Fogarty HE Leang C Franks AE Malvankar NS Lovley DR 《Science (New York, N.Y.)》2010,330(6009):1413-1415
Microbial consortia that cooperatively exchange electrons play a key role in the anaerobic processing of organic matter. Interspecies hydrogen transfer is a well-documented strategy for electron exchange in dispersed laboratory cultures, but cooperative partners in natural environments often form multispecies aggregates. We found that laboratory evolution of a coculture of Geobacter metallireducens and Geobacter sulfurreducens metabolizing ethanol favored the formation of aggregates that were electrically conductive. Sequencing aggregate DNA revealed selection for a mutation that enhances the production of a c-type cytochrome involved in extracellular electron transfer and accelerates the formation of aggregates. Aggregate formation was also much faster in mutants that were deficient in interspecies hydrogen transfer, further suggesting direct interspecies electron transfer. 相似文献
17.
18.
Digestion of the electron transport particle with phospholipase A results in the loss of its oxidative capacity. Evidence presented indicates that this is primarily due to the cleavage of the phospholipid-cytochrome c complex within the mitochondria. 相似文献
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20.
Long-range electron transfer in heme proteins 总被引：11，自引：0，他引：11
Kinetic experiments have conclusively shown that electron transfer can take place over large distances (greater than 10 angstroms) through protein interiors. Current research focuses on the elucidation of the factors that determine the rates of long-range electron-transfer reactions in modified proteins and protein complexes. Factors receiving experimental and theoretical attention include the donor-acceptor distance, changes in geometry of the donor and acceptor upon electron transfer, and the thermodynamic driving force. Recent experimental work on heme proteins indicates that the electron-transfer rate falls off exponentially with donor-acceptor distance at long range. The rate is greatly enhanced in proteins in which the structural changes accompanying electron transfer are very small. 相似文献