scholarly journals Electron transfer from Phanerochaete chrysosporium cellobiose oxidase to equine cytochrome c and Pseudomonas aeruginosa cytochrome c-551

1994 ◽  
Vol 298 (2) ◽  
pp. 329-334 ◽  
Author(s):  
M S Rogers ◽  
G D Jones ◽  
G Antonini ◽  
M T Wilson ◽  
M Brunori
Keyword(s):  
Electron Transfer ◽  
Cytochrome C ◽  
Cytochrome B ◽  
Gel Chromatography ◽  
Cytochromes C ◽  
Cellulose Breakdown ◽  
Value Decomposition ◽  
Rate Limit ◽  
Positively Charged

The electron-transfer reactions of cellobiose oxidase (CBO) have been investigated by conventional and by rapid-scan stopped-flow spectroscopy at pH 6.0. Analysis of the absorbance/time/wavelength matrix by Singular Value Decomposition (SVD) confirms earlier studies showing that cellobiose rapidly reduces the flavin group (7.7 s-1; cellobiose, 100 microM) which in turn slowly (0.2 s-1) reduces the cytochrome b moiety. In the presence of CBO, cellobiose reduces cytochromes c in a reaction that does not depend on oxygen or superoxide. The rate limit for this process is independent of the source of the cytochromes c and is identical with the rate of cytochrome b reduction. Rapid-mixing experiments show that cytochrome b may donate electrons very rapidly to either mammalian cytochrome c or bacterial cytochrome c-551. The reactions were second-order (kc = 1.75 x 10(7) M-1 x s-1; kc-551 = 4.3 x 10(6) M-1 x s-1; pH 6.0, 21 degrees C and I0.064) and strongly ionic-strength (I)-dependent: kc decreasing with I and kc-551 increasing with I. These results suggest the electron-transfer site near cytochrome b bears a significant negative charge. Equilibrium gel chromatography confirms that CBO oxidase and positively charged mammalian cytochrome c make stable complexes. These results are discussed in terms of a model suggesting an electron-transfer role for cytochrome b in vivo, possibly connected with radical-mediated cellulose breakdown.

scholarly journals Multiple light-induced reactions of cytochromes b and c in Rhodopseudomonas spheroides

1969 ◽  
Vol 114 (4) ◽  
pp. 793-799 ◽  
Author(s):  
O. T. G. Jones
Keyword(s):  
Cytochrome C ◽  
Cytochrome B ◽  
Photochemical Reaction ◽  
Room Temperature ◽  
Close Association ◽  
Antimycin A ◽  
Reaction Centre ◽  
Difference Spectra ◽  
Cytochromes C ◽  
Rhodopseudomonas Spheroides

Illumination of chromatophore preparations from Rhodopseudomonas spheroides causes the oxidation of a cytochrome c and a slight oxidation of a cytochrome b with a maximum at 560nm. When illuminated in the presence of antimycin A the oxidation of cytochrome c was more pronounced and cytochrome b560 was reduced; the dark oxidation of cytochrome b560 was biphasic in the presence of succinate, but not in the presence of NADH, a less effective reductant. Split-beam spectroscopy showed that, in addition to the reduction of cytochrome b560, another pigment with maxima at 565 and 537nm. was reduced and was more rapidly oxidized in the dark than cytochrome b560. This pigment, tentatively identified as cytochrome b565, was also detected in spectra at 77°k, after brief illumination at room temperature; the maxima at 77°k were at 562 and 536nm. In the absence of antimycin A, light caused a transient reduction of cytochrome b565 and an oxidation of cytochrome b560. Dark oxidation of b565 was rapid, even in the presence of antimycin A and succinate. Difference spectra, at 77°k, of ascorbate-reduced minus succinate-reduced chromatophores or of anaerobic succinate-reduced minus aerobic succinate-reduced chromatophores suggested that two cytochromes c were present, with maxima at 547 and 549nm. When chromatophores frozen at 77°k were illuminated both these cytochromes c were oxidized, indicating a close association with the photochemical reaction centre. A scheme involving two reaction centres is proposed to explain these results.

Preferred sites on cytochrome c for electron transfer with two positively charged blue copper proteins, Anabaena variabilis plastocyanin and stellacyanin

Biochemistry ◽  
1986 ◽  
Vol 25 (22) ◽  
pp. 6947-6951 ◽  
Author(s):  
Graeme D. Armstrong ◽  
Stephen K. Chapman ◽  
Margaret J. Sisley ◽  
A. Geoffrey Sykes ◽  
Alastair Aitken ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Cytochrome C ◽  
Anabaena Variabilis ◽  
Copper Proteins ◽  
Blue Copper Proteins ◽  
Blue Copper ◽  
Positively Charged

scholarly journals Stimulation of the respiratory chain of rat liver mitochondria between cytochrome c1 and cytochrome c by glucagon treatment of rats

1978 ◽  
Vol 172 (3) ◽  
pp. 399-405 ◽  
Author(s):  
Andrew P. Halestrap
Keyword(s):  
Cytochrome C ◽  
Cytochrome B ◽  
Respiratory Chain ◽  
Redox State ◽  
Electron Flow ◽  
Rat Liver Mitochondria ◽  
O2 Uptake ◽  
Pyruvate Metabolism ◽  
Cytochromes C ◽  
Cytochrome C1

Mitochondria from glucagon-treated rats oxidize succinate, but not ascorbate plus tetramethylphenylenediamine, faster in the uncoupled state than do control mitochondria. The rate of O2 uptake in the presence of both substrates is equal to the sum of the rates of the O2 uptake in the presence of either substrate alone. It is concluded that the mitochondrial respiratory chain is limited at some point between cytochromes b and c and that this step is regulated by glucagon. Measurement of the cytochrome spectra under uncoupled conditions in the presence of succinate and rotenone demonstrates a crossover between cytochromes c and c1 when control mitochondria are compared with those from glucagon-treated rats, cytochrome c being more oxidized and cytochrome c1 more reduced in control mitochondria. Under conditions where pyruvate metabolism is studied the control mitochondria are generally more oxidized than those from glucagon-treated rats, the redox state of cytochrome b-566 correlating with the rate of pyruvate metabolism in sucrose medium. However, when the redox state of the mitochondria is taken into account, a crossover between cytochromes c and c1 is again apparent. The spectra of the b cytochromes are complex, but cytochrome b-562 appears to become more reduced relative to cytochrome b-566 in mitochondria from glucagon-treated rats than in control mitochondria. This can be explained by the existence of a more alkaline matrix in glucagon-treated rats, the redox potential for cytochrome b being pH-sensitive. It is concluded that glucagon stimulates electron flow between cytochromes c1 and c. The physiological significance of these findings is discussed.

Pressure Tuning Voltammetry. Reaction Volumes for Electron Transfer in Cytochrome c and Ruthenium-Modified Cytochromes c

1995 ◽  
Vol 117 (9) ◽  
pp. 2600-2605 ◽  
Author(s):  
J. Sun ◽  
J. F. Wishart ◽  
R. van Eldik ◽  
R. D. Shalders ◽  
T. W. Swaddle
Keyword(s):  
Electron Transfer ◽  
Cytochrome C ◽  
Pressure Tuning ◽  
Cytochromes C ◽  
Reaction Volumes

scholarly journals Amino Acid Substitutions in the Non-Ordered Ω-Loop 70–85 Affect Electron Transfer Function and Secondary Structure of Mitochondrial Cytochrome c

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 973
Author(s):  
Rita V. Chertkova ◽  
Tatyana V. Bryantseva ◽  
Nadezhda A. Brazhe ◽  
Kseniya S. Kudryashova ◽  
Victor V. Revin ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Secondary Structure ◽  
Cytochrome C ◽  
Cd Spectroscopy ◽  
Mitochondrial Cytochrome ◽  
Proposed Model ◽  
Donor And Acceptor ◽  
Cytochromes C ◽  
Spectroscopy Studies ◽  
Mitochondrial Cytochrome C

The secondary structure of horse cytochrome c with mutations in the P76GTKMIFA83 site of the Ω-loop, exhibiting reduced efficiency of electron transfer, were studied. CD spectroscopy studies showed that the ordering of mutant structure increases by 3–6% compared to that of the WT molecules due to the higher content of β-structural elements. The IR spectroscopy data are consistent with the CD results and demonstrate that some α-helical elements change into β-structures, and the amount of the non-structured elements is decreased. The analysis of the 1H-NMR spectra demonstrated that cytochrome c mutants have a well-determined secondary structure with some specific features related to changes in the heme microenvironment. The observed changes in the structure of cytochrome c mutants are likely to be responsible for the decrease in the conformational mobility of the P76GTKMIFA83 sequence carrying mutations and for the decline in succinate:cytochrome c-reductase and cytochrome c-oxidase activities in the mitoplast system in the presence of these cytochromes c. We suggest that the decreased efficiency of the electron transfer of the studied cytochromes c may arise due to: (1) the change in the protein conformation in sites responsible for the interaction of cytochrome c with complexes III and IV and (2) the change in the heme conformation that deteriorates its optimal orientation towards donor and acceptor in complexes III and IV therefore slows down electron transfer. The results obtained are consistent with the previously proposed model of mitochondrial cytochrome c functioning associated with the deterministic mobility of protein globule parts.

scholarly journals The electron-transfer reaction between azurin and the cytochrome c oxidase from Pseudomonas aeruginosa

1977 ◽  
Vol 167 (2) ◽  
pp. 447-455 ◽  
Author(s):  
S R Parr ◽  
D Barber ◽  
C Greenwood ◽  
M Brunori
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Electron Transfer ◽  
Cytochrome C ◽  
Transfer Reaction ◽  
Electron Transfer Reaction ◽  
Difference Spectra ◽  
Flow Investigation ◽  
Internal Electron ◽  
Two Phases ◽  
Rate Limit

A stopped-flow investigation of the electron-transfer reaction between oxidized azurin and reduced Pseudomonas aeruginosa cytochrome c-551 oxidase and between reduced azurin and oxidized Ps. aeruginosa cytochrome c-551 oxidase was performed. Electrons leave and enter the oxidase molecule via its haem c component, with the oxidation and reduction of the haem d1 occurring by internal electron transfer. The reaction mechanism in both directions is complex. In the direction of oxidase oxidation, two phases assigned on the basis of difference spectra to haem c proceed with rate constants of 3.2 X 10(5)M-1-S-1 and 2.0 X 10(4)M-1-S-1, whereas the haem d1 oxidation occurs at 0.35 +/- 0.1S-1. Addition of CO to the reduced enzyme profoundly modifies the rate of haem c oxidation, with the faster process tending towards a rate limit of 200S-1. Reduction of the oxidase was similarly complex, with a fast haem c phase tending to a rate limit of 120S-1, and a slower phase with a second-order rate of 1.5 X 10(4)M-1-S-1; the internal transfer rate in this direction was o.25 +/- 0.1S-1. These results have been applied to a kinetic model originally developed from temperature-jump studies.

scholarly journals A cytochrome c methyltransferase from Crithidia oncopelti.

1982 ◽  
Vol 201 (2) ◽  
pp. 329-338 ◽  
Author(s):  
J Valentine ◽  
G W Pettigrew
Keyword(s):  
Cytochrome C ◽  
Cell Extract ◽  
Lysine Methylation ◽  
Methyltransferase Activity ◽  
Proline Residue ◽  
Cytochromes C ◽  
Lysine Residues ◽  
Low Degrees ◽  
Horse Cytochrome

The mitochondrial cytochrome c-557 of Crithidia oncopelti contains two lysine residues and an N-terminal proline residue that are methylated in vivo by the methyl group of methionine. The purified cytochrome can act as a methyl acceptor for a methyltransferase activity in the cell extract that uses S-adenosylmethionine as methyl donor. Crithidia cytochrome c-557 is by far the best substrate for this methyltransferase of those tested, in spite of the fact that methylation sites are already almost fully occupied. The radioactive uptake of [14C]methyl groups from S-adenosylmethionine occurred only at a lysine residue (-8) and the N-terminal proline residue. This methyltransferase appears to differ from that of Neurospora and yeast [Durban, Nochumson, Kim, Paik & Chan (1978) J. Biol. Chem. 253, 1427-1435; DiMaria, Polastro, DeLange, Kim & Paik (1979) J. Biol. Chem. 254, 4645-4652] in that lysine-72 of horse cytochrome c is a poor acceptor. Also, the Crithidia methyltransferase appears to be stable to carry lysine methylation much further to completion than do the enzymes from yeast and Neurospora, which produce very low degrees of methylation in native cytochromes c.

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