scholarly journals Electron transfer between azurin and cytochrone c-551 from Pseudomonas aeruginosa

1975 ◽  
Vol 145 (3) ◽  
pp. 449-457 ◽  
Author(s):  
M T Wilson ◽  
C Greenwood ◽  
M Brunori ◽  
E Antonini
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Electron Transfer ◽  
Transfer Reaction ◽  
Relaxation Times ◽  
Electron Transfer Reaction ◽  
Central Feature ◽  
Cytochrome C1 ◽  
Equilibrium Data ◽  
Spectral Distributions ◽  
Rapid Reaction

The electron-transfer reaction between azurin and cytochrome c1 isolated from Pseudomonas aeruginosa was investigated by rapid-reaction techniques. Temperture-jump studies clearly reveal two chemical relaxations, the amplitudes of which have ikentical spectral distributions, but relaxation times show different dependencies on reactant concentrations. Stopped experiments also showed complex kinetics. A model is proposed which is consistent with the kinetic and equilibrium data obtained. The central feature of this model is the proposal that two intercenvertible forms of reduced azurin exist in solution, only one of which si able to participate directly in the electron-transfer reaction with cytochrome c-551. Support for the hypothesis that two forms of reduced azurin exist is derived from studies on the electron-transfer reaction between azurin and Pseudomonas cytochrome oxidase. The possible physiological significance of such a situation is discussed.

scholarly journals A temperature-jump study of the reaction between azurin and cytochrome c-551 from Pseudomonas aeruginosa (Short Communication)

1974 ◽  
Vol 137 (1) ◽  
pp. 113-116 ◽  
Author(s):  
Maurizio Brunori ◽  
Colin Greenwood ◽  
Michael T. Wilson
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Electron Transfer ◽  
Cytochrome C ◽  
Transfer Reaction ◽  
Short Communication ◽  
Temperature Jump ◽  
Relaxation Times ◽  
Electron Transfer Reaction ◽  
Relaxation Processes ◽  
Spectral Distributions

Temperature-jump studies on the electron-transfer reaction between azurin and cytochrome c-551 clearly reveal two chemical relaxations. The amplitudes of these relaxation processes have identical spectral distributions, but the relaxation times show different dependences on the reactant concentrations. These findings are discussed in terms of possible models.

scholarly journals A temperature-jump study of the reaction between azurin and cytochrome c oxidase from Pseudomonas aeruginosa

1975 ◽  
Vol 151 (1) ◽  
pp. 185-188 ◽  
Author(s):  
M Brunori ◽  
S R Parr ◽  
C Greenwood ◽  
M T Wilson
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Electron Transfer ◽  
Cytochrome Oxidase ◽  
Cytochrome C Oxidase ◽  
Molecular Complex ◽  
Transfer Reaction ◽  
Temperature Jump ◽  
Electron Transfer Reaction ◽  
Internal Transfer ◽  
Rate Limiting

The electron-transfer reaction between azurin and the cytochrome oxidase from Pseudomonas aeruginosa was investigated by temperature-jump relaxation in the absence of O2 and in the presence of CO. The results show that: (i) reduced azurin exists in two forms in equilibrium, only one of which is capable of exchanging electrons with the Pseudomonas cytochrome oxidase, in agreement with M. T. Wilson, C. Greenwood, M. Brunori & E. Antonini (1975) (Biochem. J. 145, 449-457); (ii) the electron transfer between azurin and Pseudomonas cytochrome oxidase occurs within a molecular complex of the two proteins; this internal transfer becomes rate-limiting at high reagent concentrations.

scholarly journals The electron-transfer reaction between azurin and the cytochrome c oxidase from Pseudomonas aeruginosa

1977 ◽  
Vol 167 (2) ◽  
pp. 447-455 ◽  
Author(s):  
S R Parr ◽  
D Barber ◽  
C Greenwood ◽  
M Brunori
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Electron Transfer ◽  
Cytochrome C ◽  
Transfer Reaction ◽  
Electron Transfer Reaction ◽  
Difference Spectra ◽  
Flow Investigation ◽  
Internal Electron ◽  
Two Phases ◽  
Rate Limit

A stopped-flow investigation of the electron-transfer reaction between oxidized azurin and reduced Pseudomonas aeruginosa cytochrome c-551 oxidase and between reduced azurin and oxidized Ps. aeruginosa cytochrome c-551 oxidase was performed. Electrons leave and enter the oxidase molecule via its haem c component, with the oxidation and reduction of the haem d1 occurring by internal electron transfer. The reaction mechanism in both directions is complex. In the direction of oxidase oxidation, two phases assigned on the basis of difference spectra to haem c proceed with rate constants of 3.2 X 10(5)M-1-S-1 and 2.0 X 10(4)M-1-S-1, whereas the haem d1 oxidation occurs at 0.35 +/- 0.1S-1. Addition of CO to the reduced enzyme profoundly modifies the rate of haem c oxidation, with the faster process tending towards a rate limit of 200S-1. Reduction of the oxidase was similarly complex, with a fast haem c phase tending to a rate limit of 120S-1, and a slower phase with a second-order rate of 1.5 X 10(4)M-1-S-1; the internal transfer rate in this direction was o.25 +/- 0.1S-1. These results have been applied to a kinetic model originally developed from temperature-jump studies.

scholarly journals Electron transfer studies of a conventional redox probe in human sweat and saliva bio-mimicking conditions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
P. Krishnaveni ◽  
V. Ganesh
Keyword(s):  
Electron Transfer ◽  
Crystalline Phase ◽  
Liquid Crystalline ◽  
Transfer Reaction ◽  
Electron Transfer Reaction ◽  
Redox Couple ◽  
Liquid Crystalline Phase ◽  
Transfer Reactions ◽  
Redox Probe ◽  
Human Sweat

AbstractModern day hospital treatments aim at developing electrochemical biosensors for early diagnosis of diseases using unconventional human bio-fluids like sweat and saliva by monitoring the electron transfer reactions of target analytes. Such kinds of health care diagnostics primarily avoid the usage of human blood and urine samples. In this context, here we have investigated the electron transfer reaction of a well-known and commonly used redox probe namely, potassium ferro/ferri cyanide by employing artificially simulated bio-mimics of human sweat and saliva as unconventional electrolytes. Typically, electron transfer characteristics of the redox couple, [Fe(CN)6]3−/4− are investigated using electrochemical techniques like cyclic voltammetry and electrochemical impedance spectroscopy. Many different kinetic parameters are determined and compared with the conventional system. In addition, such electron transfer reactions have also been studied using a lyotropic liquid crystalline phase comprising of Triton X-100 and water in which the aqueous phase is replaced with either human sweat or saliva bio-mimics. From these studies, we find out the electron transfer reaction of [Fe(CN)6]3−/4− redox couple is completely diffusion controlled on both Au and Pt disc shaped electrodes in presence of sweat and saliva bio-mimic solutions. Moreover, the reaction is partially blocked by the presence of lyotropic liquid crystalline phase consisting of sweat and saliva bio-mimics indicating the predominant charge transfer controlled process for the redox probe. However, the rate constant values associated with the electron transfer reaction are drastically reduced in presence of liquid crystalline phase. These studies are essentially carried out to assess the effect of sweat and saliva on the electrochemistry of Fe2+/3+ redox couple.

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