Electron transfer between cytochrome c and the binuclear center of cytochrome oxidase

Mariana Rocha; Roger Springett

doi:10.1016/j.jtbi.2018.10.022

Electron transfer between cytochrome c and the binuclear center of cytochrome oxidase

Mariana Rocha, Roger Springett

Cardiovascular Sciences

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Abstract

The Minnaert model, which can account for the reaction kinetics between cytochrome oxidase and cytochrome c (Cytc), has been used to justify equal binding rate constants for reduced and oxidized Cytc. Here we extend the model beyond reversible binding of Cytc and its irreversible oxidation to include CuA, heme a and the oxidation cycle of the binuclear center. The model reproduces the experimental reduction of CuA and heme a during turnover and the low population of the ferryl and ferrous heme a3. It predicts that the off rate constants for reduced and oxidized Cytc can be unequal and that the non-Nernst response of CuA and heme a is due to disequilibrium between free Cytc and CuA rather than redox anticooperativity

Original language	English
Journal	Journal of Theoretical Biology
Early online date	10 Oct 2018
DOIs	https://doi.org/10.1016/j.jtbi.2018.10.022
Publication status	E-pub ahead of print - 10 Oct 2018

Keywords

Cytochrome oxidase
Enzyme kinetics
Enzyme modeling
Midpoint potential
Redox anti-cooperativity and proton pumping

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10.1016/j.jtbi.2018.10.022

Electron transfer between cytochrome c_ROCHA_Firstonline10October2018_GREEN AAM (CC BY-NC-ND)Accepted author manuscript, 1.09 MBLicence: CC BY-NC-ND

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title = "Electron transfer between cytochrome c and the binuclear center of cytochrome oxidase",

abstract = "The Minnaert model, which can account for the reaction kinetics between cytochrome oxidase and cytochrome c (Cytc), has been used to justify equal binding rate constants for reduced and oxidized Cytc. Here we extend the model beyond reversible binding of Cytc and its irreversible oxidation to include CuA, heme a and the oxidation cycle of the binuclear center. The model reproduces the experimental reduction of CuA and heme a during turnover and the low population of the ferryl and ferrous heme a3. It predicts that the off rate constants for reduced and oxidized Cytc can be unequal and that the non-Nernst response of CuA and heme a is due to disequilibrium between free Cytc and CuA rather than redox anticooperativity",

keywords = "Cytochrome oxidase, Enzyme kinetics, Enzyme modeling, Midpoint potential, Redox anti-cooperativity and proton pumping",

author = "Mariana Rocha and Roger Springett",

year = "2018",

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doi = "10.1016/j.jtbi.2018.10.022",

language = "English",

journal = "Journal of Theoretical Biology",

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TY - JOUR

T1 - Electron transfer between cytochrome c and the binuclear center of cytochrome oxidase

AU - Rocha, Mariana

AU - Springett, Roger

PY - 2018/10/10

Y1 - 2018/10/10

N2 - The Minnaert model, which can account for the reaction kinetics between cytochrome oxidase and cytochrome c (Cytc), has been used to justify equal binding rate constants for reduced and oxidized Cytc. Here we extend the model beyond reversible binding of Cytc and its irreversible oxidation to include CuA, heme a and the oxidation cycle of the binuclear center. The model reproduces the experimental reduction of CuA and heme a during turnover and the low population of the ferryl and ferrous heme a3. It predicts that the off rate constants for reduced and oxidized Cytc can be unequal and that the non-Nernst response of CuA and heme a is due to disequilibrium between free Cytc and CuA rather than redox anticooperativity

AB - The Minnaert model, which can account for the reaction kinetics between cytochrome oxidase and cytochrome c (Cytc), has been used to justify equal binding rate constants for reduced and oxidized Cytc. Here we extend the model beyond reversible binding of Cytc and its irreversible oxidation to include CuA, heme a and the oxidation cycle of the binuclear center. The model reproduces the experimental reduction of CuA and heme a during turnover and the low population of the ferryl and ferrous heme a3. It predicts that the off rate constants for reduced and oxidized Cytc can be unequal and that the non-Nernst response of CuA and heme a is due to disequilibrium between free Cytc and CuA rather than redox anticooperativity

KW - Cytochrome oxidase

KW - Enzyme kinetics

KW - Enzyme modeling

KW - Midpoint potential

KW - Redox anti-cooperativity and proton pumping

U2 - 10.1016/j.jtbi.2018.10.022

DO - 10.1016/j.jtbi.2018.10.022

M3 - Article

SN - 0022-5193

JO - Journal of Theoretical Biology

JF - Journal of Theoretical Biology

ER -

Electron transfer between cytochrome c and the binuclear center of cytochrome oxidase

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Keywords

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