Location of heme a on subunits I and II and copper on subunit II of cytochrome c oxidase.

Winter, Daryl B.; Bruyninckx, Walter J.; Foulke, F.G.; Grinich, Nicholas P.; Mason, Howard S.

doi:10.1016/s0021-9258(19)70306-8

Cited by 120 publications

(4 citation statements)

References 51 publications

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“…Subunit I, due to its large size and high a-helical content, may provide a large portion of the surface area for the contact sites (either in hydrophobic or in hydrophilic domains of the enzyme) between monomers of cytochrome c oxidase. These contact sites and the location of three of the redox centers of the enzyme in subunit I (Winter et al, 1980) may support the data of Antonini et al (1987), which suggest that the dimeric structure of the enzyme regulates its electron-transferring activity. Along these lines, Bormann and Engelman (1992) have suggested that intramembrane helix-helix association in protein oligomerization occurs in signal-transducing proteins and that conformational regulation of the oligomeric state by effectors is involved with the transmembrane signaling.…”

Section: Discussionsupporting

confidence: 87%

Detection of bovine heart mitochondrial cytochrome c oxidase dimers in Triton X-100 and phospholipid vesicles by chemical crosslinking

Estey

Prochaska²

1993

Biochemistry

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Bovine heart cytochrome c oxidase is a multisubunit enzyme whose oligomeric state is dependent on its detergent or phospholipid environment. We have utilized the cleavable, heterobifunctional cross-linking reagent N-succinimidyl 3-[(4-azidophenyl)dithio]propionate (SADP) to detect cytochrome c oxidase dimers. Monomeric or dimeric enzyme dispersed in Triton X-100 (as assessed by sedimentation velocity measurements) was reacted with SADP. A unique intersubunit cross-link having an apparent molecular mass of 136 kDa was identified in the dimeric enzyme; this product was insensitive to limited proteolysis by trypsin and contained a cross-link between two adjacent monomers. Two-dimensional NaDodSO4-PAGE (the second dimension containing beta-mercaptoethanol to cleave the cross-linking reagent) indicated that subunit I was the major component of the dimer-specific cross-link. The dimer-specific cross-link created by SADP was observed in phospholipid vesicles [cardiolipin/phosphatidylcholine (1:20, w/w)] containing dimeric (2 microM heme aa3) enzyme; a low yield of dimer-specific cross-link was observed in liposomes containing 6 microM (heme aa3) monomeric enzyme. The 136-kDa cross-link was not observed in liposomes containing 2 microM (heme aa3) monomeric enzyme. These results indicate that subunit I from each monomer may provide one site of interaction between monomers in the dimeric form of the enzyme and that cytochrome c oxidase monomers may reassociate to form dimeric complexes in phospholipid vesicles.

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Section: Discussionsupporting

confidence: 87%

Detection of bovine heart mitochondrial cytochrome c oxidase dimers in Triton X-100 and phospholipid vesicles by chemical crosslinking

Estey

Prochaska²

1993

Biochemistry

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“…This brings the number of carboxylate groups that are potentially involved in cytochrome c binding to 7, e.g., at residues 109,112, 114, 115, 157, 158, and 198. A number of lines of evidence suggest that at least one of the copper atoms in cytochrome c oxidase is located in subunit II. Winters et al (1980) found that both heme and copper were associated exclusively with subunits I and II during electrophoresis under mild denaturing conditions. Paracoccus denitrijicans cytochrome c oxidase contains two coppers and two heme a groups but only two subunits, which are immunologically cross-reactive with subunits I and II of the eukaryotic enzyme (Ludwig, 1980).…”

Section: Discussionmentioning

confidence: 96%

Identification of specific carboxylate groups on cytochrome c oxidase that are involved in binding cytochrome c

Millett¹,

Jong²,

Paulson³

et al. 1983

Biochemistry

153

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“…There is strong evidence to believe that both hemes of cytochrome oxidase are bound to subunits I and II (Capaldi et al, 1983;Wikstrom et al, 1985). This view is based on the isolation of a complex of these components under controlled denaturation conditions (Winter et al,, 1980) and by analogy with the two-subunit preparation of a cytochrome aa3 type oxidase from Paracoccus denitrificans (Ludwig & Schatz, 1980) . The isolation from the beef heart enzyme of a complex containing heme together with subunits I, II, and IV using Gdn-HCl (see Figures 6 and 7) and using urea (Freedman et al, 1979) we believe supports the above proposal.…”

Section: Discussionmentioning

confidence: 99%

Subunit dissociation and protein unfolding in the bovine heart cytochrome oxidase complex induced by guanidine hydrochloride

Hill¹,

Cook²,

Robinson³

1988

Biochemistry

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The response of cytochrome oxidase to the denaturant guanidine hydrochloride (Gdn.HCl) occurs in two stages. The first stage is a sharp transition centered at 1 M Gdn.HCl, whereas the second stage occurs from 3 to 7 M Gdn.HCl. In the first phase, changes occur in several spectroscopic properties: (1) the tryptophan fluorescence increases from 37% of that of N-acetyltryptophanamide to 85%; (2) the emission maximum shifts from 328 to 333 nm; (3) the circular dichroism (CD) signal at 222 nm diminishes by 30%; and (4) the Soret CD signal at 426 nm is completely abolished. These spectroscopic changes are accompanied by complete loss of the oxidase's steady-state electron-transfer activity. Of the 13 available sulfhydryl residues, 2 are reactive in the isolated enzyme, but this number increases to almost 10 in the first stage of denaturation. Subunits III, VIb, VIc, and VII dissociate from the protein complex at 0.5 M Gdn.HCl, but only subunit VII can be recovered after gel filtration chromatography [nomenclature according to Buse et al. (1985)]. In 2.5 M Gdn.HCl, the heme groups are found with a complex consisting predominantly of subunits I, II, and IV. In the second phase of denaturation, there is further disruption in the structure of the oxidase as indicated by continued decline in the ultraviolet CD signal and shift to longer wavelength of the tryptophan emission spectrum. However, the fluorescence quantum yield and number of reactive sulfhydryl groups decrease as the denaturant level is raised. Gel filtration chromatography reveals that protein and heme form a high molecular weight aggregate at 5 M Gdn.HCl.(ABSTRACT TRUNCATED AT 250 WORDS)

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Location of heme a on subunits I and II and copper on subunit II of cytochrome c oxidase.

Cited by 120 publications

References 51 publications

Detection of bovine heart mitochondrial cytochrome c oxidase dimers in Triton X-100 and phospholipid vesicles by chemical crosslinking

Detection of bovine heart mitochondrial cytochrome c oxidase dimers in Triton X-100 and phospholipid vesicles by chemical crosslinking

Identification of specific carboxylate groups on cytochrome c oxidase that are involved in binding cytochrome c

Subunit dissociation and protein unfolding in the bovine heart cytochrome oxidase complex induced by guanidine hydrochloride

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