scholarly journals Spectroscopic forms of carbonmonoxi-cytochrome oxidase

1979 ◽  
Vol 183 (2) ◽  
pp. 375-379 ◽  
Author(s):  
K de Fonseka ◽  
B Chance
Keyword(s):  
Low Temperature ◽  
Cytochrome Oxidase ◽  
Systematic Study ◽  
Residual Effect ◽  
Difference Spectra ◽  
Temperature Recording ◽  
Devitrification Process ◽  
Kinetics Of

A systematic study of the errors of low-temperature recording of kinetics of the cytochrome oxidase-CO reaction had identified the classic devitrification process of Keilin & Hartree [(1950) Nature (London)165, 504-505]. The methodology described here minimizes this effect, and the computation methods afford appropriate ways of detecting a residual effect. Thus it has been possible to identify that absorption difference spectra and kinetics of the reaction of fully reduced or half-reduced cytochrome oxidase with CO indicate only one spectroscopic form of the respective carbonmonoxi-cytochrome oxidase.

scholarly journals Studies on partially reduced mammalian cytochrome oxidase. Reactions with carbon monoxide and oxygen

1974 ◽  
Vol 137 (2) ◽  
pp. 205-215 ◽  
Author(s):  
Colin Greenwood ◽  
Michael T. Wilson ◽  
Maurizio Brunori
Keyword(s):  
Cytochrome Oxidase ◽  
Redox State ◽  
Mixed Valence ◽  
Order Rate Constant ◽  
Low Oxygen ◽  
Difference Spectra ◽  
Ferrocytochrome C ◽  
Kinetics Of ◽  
Enzyme Species ◽  
Binding Behaviour

A number of methods were used to prepare a species of mammalian cytochrome oxidase (EC 1.9.3.1, ferrocytochrome c–oxygen oxidoreductase) in which only cytochrome a3 is reduced and in combination with CO. The kinetics of CO binding by cytochrome a32+ in this species is significantly different from that exhibited by cytochrome a32+ in the fully reduced enzyme. The second-order rate constant for combination was 5X104m−1·s−1 and the ‘off’ constant was 3X10−2s−1. The kinetic difference spectra cytochrome a32+–cytochrome a32+–CO reveal further differences between the mixed-valence and the fully reduced enzyme. The reaction between cytochrome a32+ and oxygen in the mixed-valence species was followed in flow–flash experiments and reveals a fast, oxygen-dependent (8X107m−1·s−1 at low oxygen) rate followed by a slow process, whose rate is independent of oxygen but whose amplitude is dependent on [O2]. The fast oxygen-dependent reaction yields as the first product the so-called ‘oxygenated’ enzyme. We conclude from these experiments that the ligand-binding behaviour of cytochrome a3 depends on the redox state of its partners, a fact which represents clear evidence for site–site interaction in this enzyme. The fact that oxygen reacts rapidly with this enzyme species in which only one component, namely cytochrome a3, is reduced represents clear and unequivocal evidence that this is indeed the O2-binding site in cytochrome oxidase and may indicate that reduction of oxygen can proceed via single electron steps.

scholarly journals Oxygen kinetics of frozen cytochrome oxidase. The capacity of the oxygen pocket

1980 ◽  
Vol 185 (2) ◽  
pp. 527-530 ◽  
Author(s):  
K De Fonseka ◽  
B Chance
Keyword(s):  
Low Temperature ◽  
Cytochrome Oxidase ◽  
Limited Capacity ◽  
Oxygen Kinetics ◽  
Membrane Bound ◽  
Low Temperature Kinetics ◽  
The Difference ◽  
Kinetics Of

Low-temperature kinetics of the reaction between O2 and cytochrome oxidase suggest the existence of an O2 pocket of limited capacity in membrane-bound cytochrome oxidase, and one of larger capacity in purified cytochrome oxidase. A model is proposed to explain the difference in capacity of the pockets.

scholarly journals Low-temperature kinetics of the reactions of fully reduced membrane-bound cytochrome oxidase with oxygen in the Soret, α and near-infrared regions

1979 ◽  
Vol 177 (2) ◽  
pp. 613-621 ◽  
Author(s):  
G M Clore ◽  
E M Chance
Keyword(s):  
Magnetic Susceptibility ◽  
Low Temperature ◽  
Cytochrome Oxidase ◽  
Near Infrared ◽  
Optical Wavelength ◽  
Wavelength Scanning ◽  
Membrane Bound ◽  
Low Temperature Kinetics ◽  
Kinetics Of

The kinetics of the reaction of fully reduced membrane-bound cytochrome oxidase with O2 obtained in the Soret, alpha and near-i.r. regions were analysed, and the contributions of the three intermediates of the reaction [Clore & Chance (1978) Biochem. J. 173, 799–810] to seven wavelength pairs (430–463, 444–463, 590–630, 608–630, 740–940, 790–940 and 830–940 nm) were determined. The nature of the intermediates is discussed on the basis of the data in the present paper together with data in the literature from optical wavelength scanning, e.p.r., i.r. and magnetic-susceptibility studies.

The low temperature aluminising kinetics of hot-work tool steels

2012 ◽  
Vol 67 (2) ◽  
pp. 133-139
Author(s):  
B. Matijević ◽  
I. Kumić ◽  
T. Belić
Keyword(s):  
Low Temperature ◽  
Tool Steels ◽  
Kinetics Of ◽  
Hot Work Tool Steels

Kinetics of catalytic conversion of methanol at higher pressures

1980 ◽  
Vol 45 (12) ◽  
pp. 3402-3407 ◽  
Author(s):  
Jaroslav Bartoň ◽  
Vladimír Pour
Keyword(s):  
Low Temperature ◽  
Reaction Kinetics ◽  
Water Vapour ◽  
Kinetic Data ◽  
Catalytic Conversion ◽  
The Given ◽  
Kinetics Of

The course of the conversion of methanol with water vapour was followed on a low-temperature Cu-Zn-Cr-Al catalyst at pressures of 0.2 and 0.6 MPa. The kinetic data were evaluated together with those obtained at 0.1 MPa and the following equation for the reaction kinetics at the given conditions was derived: r = [p(CH3OH)p(H2O)]0.5[p(H2)]-1.3.

Role of Surface Reconstruction and External Ion Beam in the Growth Kinetics of III-V Molecular Beam Epitaxy

1987 ◽  
Vol 94 ◽  
Author(s):  
S. B. Ogale ◽  
M. Thomsen ◽  
A. Madhukar
Keyword(s):  
Molecular Beam Epitaxy ◽  
Low Temperature ◽  
Surface Reconstruction ◽  
Molecular Beam ◽  
Ion Beam ◽  
Growth Front ◽  
Kinetic Rates ◽  
Kinetics Of ◽  
Low Temperature Epitaxy

ABSTRACTComputer simulations of III-V molecular beam epitaxy (MBE) show that surface reconstruction induced modulation of kinetic rates could give rise to ordering in alloys. Results are also presented for the possible influence of an external ion beam in achieving low temperature epitaxy as well as smoother growth front under usual conditions.

Kinetics of Low-Temperature Aluminothermic Reduction of Iron Tantalate

2021 ◽  
Vol 12 (5) ◽  
pp. 1400-1408
Author(s):  
R. I. Gulyaeva ◽  
A. M. Klyushnikov ◽  
S. A. Petrova ◽  
L. Yu. Udoeva
Keyword(s):  
Low Temperature ◽  
Aluminothermic Reduction ◽  
Reduction Of Iron ◽  
Kinetics Of
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