Abstract
Structural and functional stability of bovine cytochrome c oxidase as a function of exposure to high hydrostatic pressure is reported. The pressure affects the stability of monomeric and dimeric enzyme quite differently. Exposure of the monomeric cytochrome c oxidase to pressures higher than 2.5 kbar causes dissociation of subunits III, VIa, VIb, VIIa with a 35-50% decrease in electron transport activity. Dimeric enzyme is more resistant to high hydrostatic pressure since subunits III and VIIa do not dissociate and the electron transport activity loss is minimal.
Highlights
Cytochrome c oxidase (CcO§; Ec 1.9.3.1) is the terminal enzyme of the inner mitochondrial electron transport chain [18]
We report the effects of hydrostatic pressure on electron transport activity and structural composition of CcO
Monomeric and dimeric CcO were prepared by manipulating the concentrations of dodecyl maltoside and sodium cholate; high concentrations of dodecyl maltoside (5–10 mM) produce monomeric CcO while a mixture of dodecyl maltoside and sodium cholate produce dimeric CcO [10]
Summary
Cytochrome c oxidase (CcO§; Ec 1.9.3.1) is the terminal enzyme of the inner mitochondrial electron transport chain [18]. Bovine heart CcO is consisted of 13 different subunits [6] and the enzyme is almost always dimeric in three-dimensional lattice as it was obtained from crystallographic data [15]. The three largest subunits (I–III) are encoded by mitochondrial DNA and are synthesized in the mitochondria. They constitute the functional core of the enzyme and include all of the redox-active centers. Treatment of CcO with physical (high hydrostatic pressure) or chemical (chaotropic agents, e.g., urea – 13, peroxidation by hydrogen peroxide – 9) factors enables to study the structural effects. We report the effects of hydrostatic pressure on electron transport activity and structural composition of CcO. Our approach is the study of pressure influence on CcO in view of different behavior of dimeric and monomeric CcO forms
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