Structural features of cytochrome oxidase

Saraste, Matti

doi:10.1017/s0033583500005588

Cited by 405 publications

(346 citation statements)

References 116 publications

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“…In contrast, the phenylalanine ring may be orientated parallel to the membrane, effectively interrupling the water array. Saraste [20] and Iwata et al [5] have suggested that an invariant ghltamic acid residue in helix VI of subunit I, Glu212 2 may be involved in the mechanism of proton translocation. In agreement with this, its change to cysteine was recently shown to inhibit proton translocation in the reconstituted cytochrome ho:~ enzyme from E. colt (wherc it is Glu'-'s¢~), with much less effect on electron transfer [17].…”

Section: Resultsmentioning

confidence: 99%

Bound water in the proton translocation mechanism of the haem‐copper oxidases

et al. 1997

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We address the molecular mechanism by which the haem-copper oxidases translocate protons. Reduction of O2 to water takes place at a haem iron-copper (CUB) centre, and protons enter from one side of the membrane through a 'channel' structure in the enzyme. Statistical-mechanical calculations predict bound water molecules within this channel, and mutagenesis experiments show that breaking this water structure impedes proton translocation. Hydrogen-bonded water molecules connect the channel further via a conserved glutamic acid residue to a histidine ligand of CuB. The glutamic acid side chain may have to move during proton transfer because proton translocation is abolished if it is forced to interact with a nearby lysine or arginine. Perturbing the CuB ligand structure shifts an infrared mode that may be ascribed to the O-H stretch of bound water. This is sensitive to mutations of the glutamic acid, supporting its connectivity to the histidine. These results suggest key roles of bound water, the glutamic acid and the histidine copper ligand in the mechanism of proton translocation.

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Section: Resultsmentioning

confidence: 99%

Bound water in the proton translocation mechanism of the haem‐copper oxidases

et al. 1997

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“…The COl protein, which is involved in the mitochondrial respiratory chain, has been divided into 25 structural regions falling into five different categories (Saraste, 1990;Lunt et a!., 1996). The sequence variability found among the Hegeter species is maximum in the last 120 nucleotides of fragment 2, which is coincident with the 3' end of the gene.…”

Section: Discussion Sequence Variationmentioning

confidence: 99%

Phylogeny of the genus Hegeter (Tenebrionidae, Coleoptera) and its colonization of the Canary Islands deduced from Cytochrome Oxidase I mitochondrial DNA sequences

1996

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The genus Hegeter comprises 23 species of darkling beetles (Tenebrionidae) endemic to the Macaronesian archipelagos, with 21 of them exclusive to the Canary Islands. We have sequenced 438 bp of the mitochondrial Cytochrome Oxidase I gene in 17 species (24 taxa) of Canarian Hegeter. Estimates of nucleotide composition, transition/transversion ratios and nucleotide change frequencies are very similar to those found in another tenebrionid Canarian genus Pimelia, indicating that similar molecular mechanisms are driving the sequence evolution. The sequence variation found allows phylogenetic analyses of the genus and the deduction of colonization patterns. These involve sequential island invasion with more rapid establishment and radiation than found in the related beetles of the genus Pimelia.

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“…The enzyme accepts electrons from ferrocytochrome c and mediates transmembrane electron transfer from the cytoplasmic side to the matrix side of the inner mitochondrial membrane and reduces dioxygen at the binuclear site [1,2]. The primary electron acceptor in Cc0 is the Cu, or heme a site near the cytosolic side and electron transfer takes place to the binuclear heme a~-Cu, active center [3,4].…”

Section: Introductionmentioning

confidence: 99%

Time‐resolved study of tryptophan fluorescence in vesicle reconstituted cytochrome oxidase

Das

Mazumdar

1993

FEBS Letters

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Time-resolved study of fluorescence decay of the tryptophan residue in bovine cytochrome c oxidase in phospholipid vesicles is reported for the first time. The effect of the redox state of the protein on its conformation has been investigated using time-resolved decay of tryptophan fluorescence in the oxidised and reduced protein. The fluorescence decay was best fitted using a discrete three exponential model. Amplitude distribution of lifetimes also showed three distinct regions in the analysis of decay profiles by the maximum entropy method (MEM). Results of the time resolved studies showed that the amplitudes as well as the lifetimes of the trytophan fluorescence remain the same for the oxidised and the reduced states of cytochrome c oxidase, indicating that the environment around tryptophan residues remains more or less unaltered on reduction of the protein.The results suggest that there is no global conformational change in the protein on electron transfer and support the possibility of the existence of local fluctuations in the protein during the redox cycle.

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Structural features of cytochrome oxidase

Cited by 405 publications

References 116 publications

Bound water in the proton translocation mechanism of the haem‐copper oxidases

Bound water in the proton translocation mechanism of the haem‐copper oxidases

Phylogeny of the genus Hegeter (Tenebrionidae, Coleoptera) and its colonization of the Canary Islands deduced from Cytochrome Oxidase I mitochondrial DNA sequences

Time‐resolved study of tryptophan fluorescence in vesicle reconstituted cytochrome oxidase

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