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 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.

Highly active and stable Au@CuxO core–shell nanoparticles supported on alumina for carbon monoxide oxidation at low temperature

RSC Advances ◽  
2016 ◽  
Vol 6 (79) ◽  
pp. 75126-75132 ◽  
Author(s):  
Weining Zhang ◽  
Qingguo Zhao ◽  
Xiaohong Wang ◽  
Xiaoxia Yan ◽  
Sheng Han ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Catalytic Activity ◽  
Low Temperature ◽  
Co Oxidation ◽  
Room Temperature ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Highly Active ◽  
Co Conversion ◽  
Core Shell Nanoparticles

Au@CuxO core–shell nanoparticles and Au@CuxO/Al2O3 used for CO oxidation at low temperature are prepared. CO conversion on Au@CuxO/Al2O3 can reach to 38% at room temperature and the catalytic activity remains unchanged after 108 hours reaction.

scholarly journals Carbon monoxide- and oxygen-reacting haemoproteins in the mitochondrial fraction from the soil amoeba Acanthamoeba castellanii. Studies at subzero temperatures

1981 ◽  
Vol 200 (2) ◽  
pp. 337-342 ◽  
Author(s):  
D Lloyd ◽  
S W Edwards ◽  
B Chance
Keyword(s):  
Carbon Monoxide ◽  
Electron Transport ◽  
Cytochrome C ◽  
Acanthamoeba Castellanii ◽  
Mitochondrial Fraction ◽  
Subzero Temperatures ◽  
Soil Amoeba ◽  
Reduced Forms

1. Mitochondria-enriched fractions of the soil amoeba Acanthamoeba castellanii contained four haemoproteins that in their reduced forms reacted with CO to give photodissociable CO complexes; these were cytochromes a 3, a 614, b- and c-type cytochromes. 2. Non-photodissociable oxygen-containing compounds were formed at temperatures between -130 and -150 degrees C after photodissociation of CO in the presence of 200 microM-O2, 3. Electron transport, indicated by the oxidation of cytochromes a + a3 and cytochrome c, did not occur until the temperature was raised to -80 degrees C.

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 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).

Survival of mouse blastocysts after low-temperature preservation under high pressure

2004 ◽  
Vol 52 (4) ◽  
pp. 479-487 ◽  
Author(s):  
Cs. Pribenszky ◽  
M. Molnár ◽  
S. Cseh ◽  
L. Solti
Keyword(s):  
Phase Transition ◽  
Hydrostatic Pressure ◽  
Low Temperature ◽  
High Hydrostatic Pressure ◽  
Room Temperature ◽  
Freezing Point ◽  
Significant Loss ◽  
Embryo Cryopreservation ◽  
Subzero Temperatures ◽  
Survival Capacity

Cryoinjuries are almost inevitable during the freezing of embryos. The present study examines the possibility of using high hydrostatic pressure to reduce substantially the freezing point of the embryo-holding solution, in order to preserve embryos at subzero temperatures, thus avoiding all the disadvantages of freezing. The pressure of 210 MPa lowers the phase transition temperature of water to -21°C. According to the results of this study, embryos can survive in high hydrostatic pressure environment at room temperature; the time embryos spend under pressure without significant loss in their survival could be lengthened by gradual decompression. Pressurisation at 0°C significantly reduced the survival capacity of the embryos; gradual decompression had no beneficial effect on survival at that stage. Based on the findings, the use of the phenomena is not applicable in this form, since pressure and low temperature together proved to be lethal to the embryos in these experiments. The application of hydrostatic pressure in embryo cryopreservation requires more detailed research, although the experience gained in this study can be applied usefully in different circumstances.

Photophysical properties of N719 and Z907 dyes, benchmark sensitizers for dye-sensitized solar cells, at room and low temperature

2021 ◽  
Vol 23 (10) ◽  
pp. 6182-6189
Author(s):  
Dariusz M. Niedzwiedzki
Keyword(s):  
Solar Cells ◽  
Low Temperature ◽  
Optical Spectroscopy ◽  
Room Temperature ◽  
Photophysical Properties ◽  
Dye Sensitized Solar Cells ◽  
Time Resolved ◽  
Dye Sensitized ◽  
Sensitized Solar Cells

Photophysical properties of N719 and Z907, benchmark Ru-dyes used as sensitizers in dye-sensitized solar cells, were studied by static and time-resolved optical spectroscopy at room temperature and 160 K.

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