The mechanism of reaction of fully reduced membrane-bound cytochrome oxidase with oxygen at 176K

1978 ◽  
Vol 175 (2) ◽  
pp. 353.b1-353.b1
Keyword(s):  
Cytochrome Oxidase ◽  
Mechanism Of Reaction ◽  
Membrane Bound

scholarly journals The mechanism of reaction of fully reduced membrane-bound cytochrome oxidase with oxygen at 176K

1978 ◽  
Vol 173 (3) ◽  
pp. 799-810 ◽  
Author(s):  
G M Clore ◽  
E M Chance
Keyword(s):  
Cytochrome Oxidase ◽  
Random Distribution ◽  
Linear Optimization ◽  
Valence States ◽  
Mechanism Of Reaction ◽  
Relative Absorption ◽  
Sequential Mechanism ◽  
Membrane Bound ◽  
Good Determination

1. The results of non-linear optimization studies on the mechanism of reaction of fully reduced cytochrome oxidase with O2 at 176K are presented. The analysis is carried out on data obtained by means of dual-wavelength multi-channel spectroscopy at three wavelength pairs (604-630, 608-630 and 830-940 nm) and at three O2 concentrations (60, 200 and 1180 micron). The only model that satisfies the triple requirement of a standard deviation within the standard error of the experimental data, good determination of the optimized parameters and a random distribution of residuals is a three-species sequential mechanism. 2. On the basis of the optimized values of the relative absorption coefficients of the intermediates at each wavelength obtained from the present paper together with data from low-temperature trapping, e.p.r. and magnetic-susceptibility studies, the possible valence states of the metal centres in each of the intermediates are discussed.

scholarly journals The kinetics and thermodynamics of the reaction of solid-state fully reduced membrane-bound cytochrome oxidase with carbon monoxide as studied by dual-wavelength multichannel spectroscopy and flash photolysis

1978 ◽  
Vol 175 (2) ◽  
pp. 709-725 ◽  
Author(s):  
G M Clore ◽  
E M Chance
Keyword(s):  
Solid State ◽  
Cytochrome Oxidase ◽  
Flash Photolysis ◽  
Linear Optimization ◽  
Dual Wavelength ◽  
Mechanism Of Reaction ◽  
Sequential Mechanism ◽  
Membrane Bound ◽  
Good Determination

1. The results of non-linear optimization studies on the mechanism of reaction of solid-state fully reduced membrane-bound cytochrome oxidase with CO over the 178–203 K range are presented. The analysis is carried out on data obtained by dual-wavelength multichannel spectroscopy at three wavelength pairs (444–463 nm, 590–630 nm and 608–630 nm), which yield three distinct progress curves. The only model that satisfies the triple requirement of a standard deviation within the standard error of the data, a random distribution of residuals and good determination of the optimized parameters is a two-species sequential mechanism: flash photolysis yields unliganded cytochrome oxidase and free CO, which then recombine to form species Ic; Ic is then converted into species IIc, which is identical with the cytochrome oxidase-CO complex existing before flash photolysis. All the thermodynamic parameters describing this model are calculated. 2. On the basis of the data obtained from this paper, together with data from potentiometric studies, magnetic susceptibility measurements and i.r. spectroscopy, the chemical identity of the species is suggested.

scholarly journals Low-temperature kinetics of the reaction of oxygen and solubilized cytochrome oxidase

1978 ◽  
Vol 171 (3) ◽  
pp. 787-798 ◽  
Author(s):  
B Chance ◽  
C Saronio ◽  
J S Leigh ◽  
W J Ingledew ◽  
T E King
Keyword(s):  
Cytochrome Oxidase ◽  
Mixed Valence ◽  
Similar Species ◽  
Absorption Bands ◽  
Compound C ◽  
Valence States ◽  
Membrane Bound ◽  
Peroxy Compounds ◽  
Band Characteristic ◽  
Kinetics Of

The reaction of solubilized cytochrome oxidase in the fully reduced state with O2 at low temperatures reveals components with characteristics similar to those observed with the membrane-bound oxidase, namely compounds A and B, which are proposed to be ‘oxy’ and ‘peroxy’ compounds respectively. Similar species are identified in both solubilized and membrane-bound oxidases; the reaction velocity constant for the reation with O2 and the dissociation constant are decreased 2-3-fold in the solubilied preparation as compared with the membrane-bound species, owing to decreased reactivity towards O2 in the former. The oxidase prepared in the mixed-valence state shows the distinctive absorption band characteristic of compound C, identified in the membrane-bound oxidase. The assignment of the alpha, beta, gamma and near-i.r. absorption bands to possible valence states of these compounds is made.

scholarly journals The mechanism of reaction of ferricyanide-pretreated mixed-valence-state membrane-bound cytochrome oxidase with oxygen at 173 K

1978 ◽  
Vol 173 (3) ◽  
pp. 811-820 ◽  
Author(s):  
G M Clore ◽  
E M Chance
Keyword(s):  
Cytochrome Oxidase ◽  
Valence State ◽  
Linear Optimization ◽  
Mixed Valence ◽  
Mixed Valence State ◽  
Optical Wavelength ◽  
Valence States ◽  
Mechanism Of Reaction ◽  
Sequential Mechanism ◽  
Good Determination

1. The results of non-linear optimization studies on the mechanism of reaction of ferricyanide-pretreated mixed-valence-state cytochrome oxidase with O2 at 173 K are presented. The analysis is carried out on data obtained by means of dual-wavelength multi-channel spectroscopy at four wavelength pairs (444-463 nm, 604-630 nm, 608-630 nm and 830-940 nm) and at two O2 concentrations (360 micron and 520 micron). The only model that satisfies the triple requirement of a standard deviation within the standard error of the experimental data, a random distribution of residuals and good determination of the optimized parameters, is a three-intermediate sequential mechanism. 2. On the basis of the optimized values of the relative absorption coefficients of the intermediates at each wavelength obtained from the present paper together with data from optical wavelength scanning and e.p.r. spectroscopy obtained by low-temperature trapping studies, the possible valence states of the metal centres in each of the intermediates are discussed.

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.

Effect of lipids on the membrane-bound cytochrome oxidase of cyanobacteria

1981 ◽  
Vol 68 (11) ◽  
pp. 575-575 ◽  
Author(s):  
G. A. Peschek ◽  
G. Schmetterer
Keyword(s):  
Cytochrome Oxidase ◽  
Membrane Bound
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