scholarly journals Mechanism of proton translocation by cytochrome c oxidase: a new four-stroke histidine cycle11Amino acid residues are numbered according to the subunit I structure of cytochrome aa3 from bovine heart mitochondria.

2000 ◽  
Vol 1458 (1) ◽  
pp. 188-198 ◽  
Author(s):  
Mårten Wikström
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Proton Translocation ◽  
Heart Mitochondria ◽  
Cytochrome Aa3 ◽  
Bovine Heart

scholarly journals Proton-transfer pathways in the mitochondrial S. cerevisiae cytochrome c oxidase

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Markus L. Björck ◽  
Jóhanna Vilhjálmsdóttir ◽  
Andrew M. Hartley ◽  
Brigitte Meunier ◽  
Linda Näsvik Öjemyr ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Proton Transfer ◽  
Cytochrome C Oxidase ◽  
Proton Pumping ◽  
Heart Mitochondria ◽  
Negative Side ◽  
Bovine Heart ◽  
Proton Uptake ◽  
Mammalian Counterpart ◽  
Kinetics Of

AbstractIn cytochrome c oxidase (CytcO) reduction of O2 to water is linked to uptake of eight protons from the negative side of the membrane: four are substrate protons used to form water and four are pumped across the membrane. In bacterial oxidases, the substrate protons are taken up through the K and the D proton pathways, while the pumped protons are transferred through the D pathway. On the basis of studies with CytcO isolated from bovine heart mitochondria, it was suggested that in mitochondrial CytcOs the pumped protons are transferred though a third proton pathway, the H pathway, rather than through the D pathway. Here, we studied these reactions in S. cerevisiae CytcO, which serves as a model of the mammalian counterpart. We analyzed the effect of mutations in the D (Asn99Asp and Ile67Asn) and H pathways (Ser382Ala and Ser458Ala) and investigated the kinetics of electron and proton transfer during the reaction of the reduced CytcO with O2. No effects were observed with the H pathway variants while in the D pathway variants the functional effects were similar to those observed with the R. sphaeroides CytcO. The data indicate that the S. cerevisiae CytcO uses the D pathway for proton uptake and presumably also for proton pumping.

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