Studies on reconstituted quinol oxidase
Studies on reconstituted quinol oxidase
The aim of this study was to elucidate the mode of action of
cytochrome c in mediating electron transfer from ubiquinol-cytochrome c
reductase (Complex III) to cytochrome c oxidase (Complex IV). The overall
reaction has been referred to as quinol oxidase activity.
A preliminary investigation of the kinetics of quinol
oxidase activity in submitochondrial particles showed them to be too complex to
analyse satisfactorily. The two enzymes were therefore purified from beef heart
and a reconstituted system, involving both Complexes III and IV and cytochrome
c, established and characterised.
The kinetics of reconstituted quinol oxidase were examined
under a variety of conditions using: high and low lipid to protein ratios;
various molar ratios of Complex III to Complex IV and several ratios of
cytochrome c to enzyme. A theoretical model has been developed from these data.
A covalent cytochrome c - cytochrome c oxidase complex was
prepared to examine the necessity for cytochrome c diffusion. Although active
with artificial electron donors, the complex was ineffective in the
reconstitution of quinol oxidase activity.
The effect of a lipid phase transition on quinol oxidase
activity was examined using enzymes whose natural lipid had been replaced by
dimyristoylphosphatidylcholine. The data obtained showed cytochrome c diffusion
to be required for quinol oxidase activity.
Spin labelled derivatives of the three proteins (Complexes
III and IV and cytochrome c) were prepared and used to examine the rotational
motion of these components under various conditions using electron spin
resonance spectroscopy.
Based on these results a mechanism for the action of
cytochrome c as an intermediary electron carrier in quinol oxidase has been
proposed. The mechanism envisages cytochrome c as a mobile, lipid associated
pool mediating electron transfer between separate, freely diffusing molecules
of Complex III and Complex IV.
University of Southampton
Froud, Rosemary Jane
c9bb0b65-315f-4247-8eba-de59f3cdafd7
1983
Froud, Rosemary Jane
c9bb0b65-315f-4247-8eba-de59f3cdafd7
Ragan, Ian
15fb6293-ea66-4f8f-a79f-8ea9959ccaba
Froud, Rosemary Jane
(1983)
Studies on reconstituted quinol oxidase.
University of Southampton, Doctoral Thesis, 366pp.
Record type:
Thesis
(Doctoral)
Abstract
The aim of this study was to elucidate the mode of action of
cytochrome c in mediating electron transfer from ubiquinol-cytochrome c
reductase (Complex III) to cytochrome c oxidase (Complex IV). The overall
reaction has been referred to as quinol oxidase activity.
A preliminary investigation of the kinetics of quinol
oxidase activity in submitochondrial particles showed them to be too complex to
analyse satisfactorily. The two enzymes were therefore purified from beef heart
and a reconstituted system, involving both Complexes III and IV and cytochrome
c, established and characterised.
The kinetics of reconstituted quinol oxidase were examined
under a variety of conditions using: high and low lipid to protein ratios;
various molar ratios of Complex III to Complex IV and several ratios of
cytochrome c to enzyme. A theoretical model has been developed from these data.
A covalent cytochrome c - cytochrome c oxidase complex was
prepared to examine the necessity for cytochrome c diffusion. Although active
with artificial electron donors, the complex was ineffective in the
reconstitution of quinol oxidase activity.
The effect of a lipid phase transition on quinol oxidase
activity was examined using enzymes whose natural lipid had been replaced by
dimyristoylphosphatidylcholine. The data obtained showed cytochrome c diffusion
to be required for quinol oxidase activity.
Spin labelled derivatives of the three proteins (Complexes
III and IV and cytochrome c) were prepared and used to examine the rotational
motion of these components under various conditions using electron spin
resonance spectroscopy.
Based on these results a mechanism for the action of
cytochrome c as an intermediary electron carrier in quinol oxidase has been
proposed. The mechanism envisages cytochrome c as a mobile, lipid associated
pool mediating electron transfer between separate, freely diffusing molecules
of Complex III and Complex IV.
Text
Froud 1983 Thesis
- Version of Record
More information
Published date: 1983
Identifiers
Local EPrints ID: 473983
URI: http://eprints.soton.ac.uk/id/eprint/473983
PURE UUID: 25105a78-923b-4074-b550-59aac15e17d5
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Date deposited: 07 Feb 2023 17:35
Last modified: 16 Mar 2024 21:03
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Contributors
Author:
Rosemary Jane Froud
Thesis advisor:
Ian Ragan
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