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.

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 Carbon monoxide-reacting haemoproteins in the mitochondrial fraction of Acanthamoeba castellanii

1980 ◽  
Vol 186 (3) ◽  
pp. 669-678 ◽  
Author(s):  
S W Edwards ◽  
D Lloyd
Keyword(s):  
Carbon Monoxide ◽  
Low Temperature ◽  
Room Temperature ◽  
Acanthamoeba Castellanii ◽  
Mitochondrial Fraction ◽  
Submitochondrial Particles ◽  
Difference Spectra ◽  
Intact Cells ◽  
Mitochondrial Fractions ◽  
Eukaryotic Organisms

1. Room-temperature (18 degrees C) CO difference spectra of mitochondrial fractions from the amoeba Acanthamoeba castellanii reveal the presence of at least four CO-reacting haemoproteins. As well as cytochrome a3, other components reacting with CO are: (i) a c-type cytochrome; (ii) a b-type cytochrome; and (iii) another a-type cytochrome. 2. The same components can be identified in low-temperature photodissociation experiments with intact cells or mitochondria. 3. The time of exposure to CO and the nature of the reductant are both important in identifying all the components present, in that the b-type cytochrome is more readily distinguished after longer exposure to CO and more of the c-type cytochrome is detectable when NADH is the reductant 4. Treatment of mitochondria with ultrasound releases two components, identifiable in low-temperature difference spectra as a c-type and a b-type cytochrome; only the latter appears to have any reaction with CO, and the CO-reacting c-type cytochrome is retained in submitochondrial particles. 5. The complexity of the CO-reacting haemoproteins in this organism is compared with the simpler systems found in other eukaryotic organisms.

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.

The action spectrum of hemoprotein oxidase in Nitrobacter agilis

1969 ◽  
Vol 47 (5) ◽  
pp. 507-509 ◽  
Author(s):  
Joan E. Hill ◽  
C P. S. Taylor
Keyword(s):  
Room Temperature ◽  
Action Spectrum ◽  
Terminal Oxidase ◽  
Height Ratio ◽  
Cytochrome O ◽  
Half Height ◽  
Nitrobacter Agilis ◽  
The Many ◽  
Half Height Width ◽  
Photochemical Action

A photochemical action spectrum for the relief by light of the carbon monoxide inhibition of respiration in Nitrobacter agilis (ATCC No. 14123) has been determined by the method of Castor and Chance, the first such determination in a chemolithotrophic organism. The cells were grown at 30 °C in liquid culture, were used when consuming 2–4 mM/ml per day of nitrite, and were concentrated by centrifuging. They respired actively at room temperature for about 3 h in air but only 75 min in the CO:O2 (4:1) mixture. Consistent γ and α bands of a hemoprotein spectrum were obtained from the combined results of two cultures. The maxima are at 432 ± 2 and 592 ± 2 nm; the γ/α height ratio is 6.4 (±22%) and the half-height width of the γ band is 15 nm. Since cytochrome a1 but not a3 has been reported in several Nitrobacter studies, the conclusion is that an a1-type cytochrome is a terminal oxidase in Nitrobacter agilis. The great scatter in the points around the β peak presumably results from the many cultures used, and possibly from differing oxidase activities in different phases of growth. The breadth of the peak could result from the presence of cytochrome o in some cultures. The possibility of more than one terminal oxidase is not excluded.

scholarly journals Oxygen affinity of the respiratory chain of Acanthamoeba castellanii

1983 ◽  
Vol 214 (1) ◽  
pp. 47-51 ◽  
Author(s):  
D Lloyd ◽  
H Mellor ◽  
J L Williams
Keyword(s):  
Plasma Membrane ◽  
Cytochrome C ◽  
Cytochrome B ◽  
Respiratory Chain ◽  
Oxygen Affinity ◽  
Acanthamoeba Castellanii ◽  
Intact Cells ◽  
Cytochrome Aa3 ◽  
Isolated Mitochondria ◽  
Soil Amoeba

Apparent Km values for O2 for the soil amoeba Acanthamoeba castellanii determined polarographically and by bioluminescence gave similar values (0.37 and 0.41 microM respectively). Mitochondria oxidizing succinate or NADH in the presence or absence of ADP gave values in the range 0.21-0.36 microM-O2. Oxidation of respiratory-chain components to 50% of the aerobic steady states in intact cells was observed at the following O2 concentrations: cytochrome aa3, 0.1-0.25 microM; cytochrome c, 0.3-0.6 microM; cytochrome b, 0.35-0.45 microM; flavoprotein, 2 microM. In isolated mitochondria corresponding values for a-, c- and b-type cytochromes were 0.007, 0.035-0.05 and 0.06-0.09 microM-O2. It is concluded that an O2 gradient exists between plasma membrane and mitochondria in A. castellanii.

scholarly journals Haemoprotein terminal oxidases in the nematodes Nippostrongylus brasiliensis and Ascaridia galli

1988 ◽  
Vol 256 (1) ◽  
pp. 295-298 ◽  
Author(s):  
T A Paget ◽  
M Fry ◽  
D Lloyd
Keyword(s):  
Muscle Tissue ◽  
Endogenous Respiration ◽  
Nippostrongylus Brasiliensis ◽  
Reproductive Tissue ◽  
Ascaridia Galli ◽  
Difference Spectra ◽  
Cytochrome Aa3 ◽  
Action Spectra ◽  
Terminal Oxidases ◽  
Photochemical Action

1. Mitochondria isolated from the gut-dwelling nematodes Nippostrongylus brasiliensis and Ascaridia galli (muscle and gut + reproductive tissue) were examined for cytochromes, and it was observed that N. brasiliensis and A. galli muscle tissue mitochondria contained a-, b- and c-type cytochromes, but their stoichiometries were quite different (1:2:1.9 and 1:11.4:13.6 respectively); A. galli gut + reproductive-tissue mitochondria, however, only contained b and c cytochromes, in a ratio of 1:0.8. 2. CO difference spectra showed the presence of CO-reacting b-type cytochrome(s) in all three types of mitochondria; the fast-reacting species comprised 30, 44 and 39% of the total in N. brasiliensis, A. galli muscle and A. galli gut + reproductive-tissue mitochondria respectively. 3. Cytochrome aa3 was observed in N. brasiliensis mitochondria and in those from A. galli muscle, but was below the level of detectability (less than 0.005 nmol/mg of protein) for A. galli gut + reproductive-tissue mitochondria. 4. Photochemical action spectra for the reversal of CO inhibition of the endogenous respiration of whole worms (at 24 microM- and 40 microM-O2 respectively for N. brasiliensis and A. galli) gave maxima at 598 and 542-543 nm, corresponding to the alpha- and beta-absorption maxima of cytochrome aa3, and at 567 nm (b-type cytochrome) for both worms. These results suggest that cytochrome aa3 is the major functional oxidase in N. brasiliensis, whereas the CO-reacting b-type cytochrome dominates in A. galli.

scholarly journals The cytochromes of Acanthamoeba castellanii

1977 ◽  
Vol 168 (1) ◽  
pp. 113-121 ◽  
Author(s):  
S W Edwards ◽  
A H Chagla ◽  
A J Griffiths ◽  
D Lloyd
Keyword(s):  
Low Temperature ◽  
Acanthamoeba Castellanii ◽  
Difference Spectrum ◽  
Cell Respiration ◽  
Difference Spectra ◽  
Whole Cells ◽  
Microsomal Membranes ◽  
Cytochrome P 450 ◽  
Photochemical Action ◽  
Soret Absorption

1. Low-temperature difference spectra of gradient-purified mitochondria of Acanthamoeba castellanii reveal the presence of cytochromes b-555, b-562 and c-549, with a-type cytochromes having a broad asymmetrical maximum at 602 nm; these components were also observed in specta of whole cells. 2. The a-type cytochromes are unusual in that they have split Soret absorption maxima (at 442 and 449 nm) and an uncharacteristic CO difference spectrum. 3. CO difference spectra of whole cells and ‘microsomal’ membranes show large amounts of cytochrome P-420 compared with cytochrome P-450. 4. Difference spectra in the presence of cyanide indicate the presence of an a-type cytochrome and two cyanide-reacting components, one of which may be cytochrome a3. 5. Whole-cell respiration in a N2/O2 (19:1) atmosphere was decreased by 50%, suggesting the presence of a low-affinity oxidase. This lowered respiration is inhibited by 50% by CO, and the inhibition is partially light-reversible; photochemical action spectra suggest that cytochrome a3 contributes to this release of inhibition. Other CO-reacting oxidases are also present. 6. The results are discussed with the view that cytochrome a3 is present in A. castellanii, but its identification in CO difference spectra is obscured by other component(s).

scholarly journals Cytochrome a620 in Tetrahymena pyriformis. Reactions with carbon monoxide and oxygen at subzero temperatures and photochemical action spectra

1982 ◽  
Vol 206 (2) ◽  
pp. 367-372 ◽  
Author(s):  
D Lloyd ◽  
R I Scott ◽  
S W Edwards ◽  
C Edwards ◽  
B Chance
Keyword(s):  
Electron Transport ◽  
Tetrahymena Pyriformis ◽  
Terminal Oxidase ◽  
Ciliate Protozoan ◽  
Whole Cells ◽  
Action Spectra ◽  
Terminal Oxidases ◽  
Subzero Temperatures ◽  
Electron Transport Chains ◽  
Photochemical Action

1. Mitochondria-enriched fractions of the ciliate protozoan Tetrahymena pyriformis ST contained CO-reacting cytochromes b560 and a620. 2. A non-photodissociable oxygen-containing compound of cytochrome a620 was formed in whole cell suspensions at −114 degrees C after photolysis of CO in the presence of 200 microM-O2. 3. Electron transport, indicated by the oxidation of cytochrome a620 and cytochrome c, occurred at temperatures higher than −72 degrees C. 4. Photochemical action spectra for the relief of respiratory inhibition of whole cells by CO obtained by using a liquid dye laser indicate that the only CO-reacting terminal oxidase detectable was cytochrome a620. 5. It is concluded that the alternative electron transport chains in this organism utilize non-cytochrome terminal oxidases.

Oxidation of formate by mycobacteria of the Scrofulaceum group

1978 ◽  
Vol 24 (12) ◽  
pp. 1548-1552
Author(s):  
M. Ishaque ◽  
S. J. Kim ◽  
L. Kato
Keyword(s):  
Cytochrome B ◽  
Absorption Maximum ◽  
Redox State ◽  
Formate Dehydrogenase ◽  
Complete Oxidation ◽  
Difference Spectra ◽  
Intact Cells ◽  
Oxidase System ◽  
Formate Oxidation ◽  
A Value

Intact cells obtained from Mycobacterium scrofulaceum as well as from mycobacterial strains M.A6 and M.R56 isolated respectively from leprous tissues of armadillo and rat leproma and grown with glycerol as the oxidizable substrate catalyzed complete oxidation of formate. The stoichiometry of formate oxidase system yielded a value of 2 mol of CO2 produced per mole of O2 or per 2 moles of formate consumed. Cell-free preparations from these three strains of mycobacteria contained formate dehydrogenase which was associated exclusively in the particulate fraction. Formate oxidation was markedly stimulated by small amounts of selenite and molybdate added together. Formate-reduced minus oxidized difference spectra disclosed cytochromes of the b type while spectral evidence did not suggest the existence of cytochromes a or c components. The effect of 2-N-heptyl-4-hydroxyquinoline-N-oxide on the redox state of cytochromes indicated that formate oxidation was mediated by cytochrome b with absorption maximum of 556 nm and not of 562 nm.

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