2012
DOI: 10.1021/bi201795c
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The Membrane Modulates Internal Proton Transfer in Cytochrome c Oxidase

Abstract: The functionality of membrane proteins is often modulated by the surrounding membrane. Here, we investigated the effect of membrane reconstitution of purified cytochrome c oxidase (CytcO) on the kinetics and thermodynamics of internal electron and proton-transfer reactions during O(2) reduction. Reconstitution of the detergent-solubilized enzyme in small unilamellar soybean phosphatidylcholine vesicles resulted in a lowering of the pK(a) in the pH dependence profile of the proton-uptake rate. This pK(a) change… Show more

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Cited by 22 publications
(17 citation statements)
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“…The activity of cytochrome c oxidase is dependent on lipid composition, but primarily when changing the hydrocarbon chain length 35 (for review see also 36 ). In a recent study we found that the rate of specific proton-coupled electron transfer steps in cytochrome c oxidase are dependent on the presence of a surrounding membrane (as compared to detergent-solubilized oxidase), however, the reaction steps that are most strongly affected by changing the lipid composition ( 15 16 , e.g. proton uptake during reduction and the so-called P → F reaction, τ ≅ 100 μs 37 ), are not rate-limiting for the overall turnover for the membrane-reconstituted oxidase.…”
Section: Discussionmentioning
confidence: 99%
See 1 more Smart Citation
“…The activity of cytochrome c oxidase is dependent on lipid composition, but primarily when changing the hydrocarbon chain length 35 (for review see also 36 ). In a recent study we found that the rate of specific proton-coupled electron transfer steps in cytochrome c oxidase are dependent on the presence of a surrounding membrane (as compared to detergent-solubilized oxidase), however, the reaction steps that are most strongly affected by changing the lipid composition ( 15 16 , e.g. proton uptake during reduction and the so-called P → F reaction, τ ≅ 100 μs 37 ), are not rate-limiting for the overall turnover for the membrane-reconstituted oxidase.…”
Section: Discussionmentioning
confidence: 99%
“…For example, membrane surface groups may be involved in lateral proton transfer that would compete kinetically with transfer via bulk water. This phenomenon has been addressed in the past in a number of experimental and theoretical studies 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 . For example, in a landmark study with purple membranes of H. salinarium , Heberle et al .…”
mentioning
confidence: 99%
“…Recently it was reported that the membrane modulates internal proton transfer in cytochrome c oxidase. 32) Hence it is possible that the membrane lipid composition affected the activity of the terminal oxidases. On the other hand, higher piezotolerance of the oxidase activity of S. violacea grown under higher pressure is perhaps a result of the properties of the pressure-induced terminal oxidase and not of changes in lipid composition during growth under high pressure.…”
Section: Discussionmentioning
confidence: 99%
“…Since the activity of many enzymes is strongly dependent on the enzyme’s immediate environment [ 19 , 20 , 21 ], this raises the question to what extent the catalytic activity of C c O is affected by the lipid composition of the hosting membrane [ 22 ], in particular, as the known lipid binding sites of C c O also show high conservation across species [ 23 ]. Moreover, previous studies using a similar enzyme show an influence of membrane composition on enzymatic activity and proton translocation along the membrane [ 24 , 25 ]. Motivated by these considerations, we set out to investigate the influence of the lipid environment on the proton turnover rate of R. sphaeroides C c O.…”
Section: Introductionmentioning
confidence: 95%