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.

Occurrence of c-Type Cytochrome in Mycobacterium lepraemurium

1974 ◽  
Vol 52 (11) ◽  
pp. 991-996 ◽  
Author(s):  
M. Ishaque ◽  
L. Kato
Keyword(s):  
Absorption Spectrum ◽  
Cytochrome C ◽  
Cytochrome B ◽  
Antimycin A ◽  
Alpha Band ◽  
Difference Spectra ◽  
Absorption Bands ◽  
Type C ◽  
The Difference ◽  
Mycobacterium Lepraemurium

The existence of c-type cytochrome in Mycobacterium lepraemurium was examined. The dithionite-treated cell-free extracts exhibited absorption peaks of cytochromes a + a3 and b, whereas the alpha band of c-type cytochrome at 552 nm was obscured by the large absorption peak of cytochrome b at 560 nm. The addition of NADH, NADPH, or succinate to cell-free extracts caused the reduction of b- and c-type cytochromes to nearly the same extent and thus the difference spectra displayed distinct separate peaks of b- and c-type cytochromes at 562 and 552 nm, respectively. The cell-free extracts treated with ascorbate showed absorption bands of cytochrome types c and a + a3, whereas the addition of succinate to a system preinhibited by antimycin A revealed the absorption bands of cytochrome b only. The absorption spectrum of the pyridine hemochromogens of M. lepraemurium was similar to that of mammalian cytochrome c. The results clearly indicated that, in addition to cytochromes of the a + a3 and b type, c-type cytochrome is also present in M. lepraemurium.

scholarly journals Photochemical action spectra indicate that cytochrome a/a3 is the predominant haemoprotein terminal oxidase in Acanthamoeba castellanii

1983 ◽  
Vol 210 (3) ◽  
pp. 721-725 ◽  
Author(s):  
R I Scott ◽  
D Lloyd
Keyword(s):  
Cytochrome B ◽  
Room Temperature ◽  
Stationary Phases ◽  
Acanthamoeba Castellanii ◽  
Terminal Oxidase ◽  
Difference Spectra ◽  
Intact Cells ◽  
Action Spectra ◽  
Stages Of Growth ◽  
Photochemical Action

1. Room-temperature CO-reduced minus reduced difference spectra of intact cells of Acanthamoeba castellanii show the presence of CO-reacting haemoproteins in cells from the early-exponential, late-exponential and stationary phases of growth. 2. The relative rates of reaction with CO of the two haemoproteins differ; that of cytochrome a/a3 with CO is complete within 1 min of bubbling with CO, whereas that of cytochrome b takes longer than 90 min. 3. Photochemical action spectra reveal cytochrome a/a3 as the predominant haemoprotein oxidase at all stages of growth. 4. It is concluded that the alternative oxidases known to be present in these organisms are not cytochromes.

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.

Photoreaction of tyrosin-iodinated bacteriorhodopsin at low temperature

1982 ◽  
Vol 2 (11) ◽  
pp. 949-958 ◽  
Author(s):  
Tatsuo Iwasa ◽  
Kazuo Takeda ◽  
Fumio Tokunaga ◽  
Peter S. Scherrer ◽  
Lester Packer
Keyword(s):  
Low Temperature ◽  
Proton Pump ◽  
Photochemical Reaction ◽  
Room Temperature ◽  
Green Light ◽  
Glycerol Solution ◽  
Difference Spectra ◽  
Tyrosine Residues ◽  
The Difference

To elucidate the role of tyrosine residues in the shift of λmax and the light-driven proton pump of bacteriorhodopsin, the photochemical reaction of tyrosine-iodinated bacteriorhodopsin (tyr-mod-bR) was investigated by low-temperature spectrophotometry. After 4–5 of 11 tyrosine residues of bacteriorhodopsin were iodinated, the meta-intermediate of tyr-mod-bR in 75% glycerol solution became so stable that its decay could be observed even at room temperature and it was stable in the dark for several hours at −65°C. Four batho-intermediates were formed by irradiation with green light (500 nm) at −170°C. Like native bacteriorhodopsin, these batho-intermediates were photoreversible at −170°C. Four corresponding meta-intermediates were also formed by irradiation at −60°C. Using the difference spectra between meta-intermediates and tyr-mod-bR, the absorption spectra of four kinds of tyr-mod-bRs, batho-intermediates, and meta-intermediates were estimated. Each was at shorter wavelengths than that of its corresponding type in native bacteriorhodopsin. The results indicate that two or more tyrosine residues have some role in determining color in native bacteriorhodopsin.

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.

CO-reacting haemoproteins of neutrophils: Evidence for cytochrome b-245 and myeloperoxidase as potential oxidases during the respiratory burst

1987 ◽  
Vol 7 (3) ◽  
pp. 193-199 ◽  
Author(s):  
Steven W. Edwards ◽  
David Lloyd
Keyword(s):  
Cytochrome B ◽  
Respiratory Burst ◽  
Absorption Maximum ◽  
Room Temperature ◽  
Polymorphonuclear Leucocytes ◽  
O2 Uptake ◽  
Difference Spectra ◽  
Action Spectra ◽  
Photochemical Action

Room temperature, CO-difference spectra of intact rat polymorphonuclear leucocytes (neutrophils) revealed the presence of a number of CO-binding haemoproteins. Absorption maxima at 413, 540 and 570 nm were attributed to the CO-complex of cytochrome b-245 whereas an absorption maximum at 595 nm was assigned to the contribution from a myeloperoxidase complex, since an identical absorption maximum was observed in CO-difference spectra of purified myeloperoxidase in the presence of H2O2. Photochemical action spectra for the relief of CO-inhibited O2 uptake revealed contributions from both cytochrome b-245 and myeloperoxidase. The potential of these two O2- and CO-binding haemoproteins to function as oxidases during the respiratory burst is discussed.

scholarly journals Comparison of yeast and beef cytochrome c oxidases. Kinetics and binding of horse, fungal, and Euglena cytochromes c.

1979 ◽  
Vol 254 (23) ◽  
pp. 11973-11981 ◽  
Author(s):  
J.K. Dethmers ◽  
S. Ferguson-Miller ◽  
E. Margoliash
Keyword(s):  
Cytochrome C ◽  
Cytochromes C

scholarly journals Multiple low spin forms of the cytochrome c ferrihemochrome. EPR spectra of various eukaryotic and prokaryotic cytochromes c.

1977 ◽  
Vol 252 (2) ◽  
pp. 574-582 ◽  
Author(s):  
D L Brautigan ◽  
B A Feinberg ◽  
B M Hoffman ◽  
E Margoliash ◽  
J Preisach ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Epr Spectra ◽  
Cytochromes C

scholarly journals Properties of a cytochrome c-enriched light particulate fraction isolated from the photosynthetic bacterium Rhodopseudomonas spheroides

1978 ◽  
Vol 174 (1) ◽  
pp. 267-275 ◽  
Author(s):  
J Barrett ◽  
C N Hunter ◽  
O T G Jones
Keyword(s):  
Cytochrome C ◽  
Sodium Dodecyl ◽  
Photosynthetic Bacterium ◽  
Particulate Fraction ◽  
Cytochrome C Reductase ◽  
Cytochrome C2 ◽  
Succinate Cytochrome C Reductase ◽  
Bulk Membrane ◽  
Nadh Cytochrome ◽  
Rhodopseudomonas Spheroides

Differential centrifugation of suspensions of French-press-disrupted Rhodopseudomonas spheroides yielded a light particulate fraction that was different in many properties from the bulk membrane fraction. It was enriched in cytochrome c and had a low cytochrome b content. When prepared from photosynthetically grown cells this fraction had a very low specific bacteriochlorophyll content. The cytochrome c of the light particles differed in absorption maxima at 77K from cytochrome c2 attached to membranes; there was pronounced splitting of the alpha-band, as is found in cytochrome c2 free in solution. Potentiometric titration at A552–A540 showed the presence of two components that fitted an n = 1 titration; one component had a midpoint redox potential of +345mV, like cytochrome c2 in solution, and the second had E0′ at pH 7.0 of +110 mV, and they were present in a ratio of approx. 2:3. Difference spectroscopy at 77K showed that the spectra of the two components were very similar. More of a CO-binding component was present in particles from photosynthetically grown cells. Light membranes purified by centrifugation on gradients of 5–60% (w/w) sucrose retained the two c cytochromes; they contained no detectable succinate-cytochrome c reductase or bacteriochlorophyll and very little ubiquinone, but they contained NADH-cytochrome c reductase and some phosphate. Electrophoresis on sodium dodecyl sulphate/polyacrylamide gels showed that the light membranes of aerobically and photosynthetically grown cells were very similar and differed greatly from other membrane fractions of R. spheroides.

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