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rdf:type |
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lifeskim:mentions |
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pubmed:issue |
30
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pubmed:dateCreated |
2005-7-27
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pubmed:abstractText |
The membrane-bound enzyme cytochrome c oxidase is responsible for cell respiration in aerobic organisms and conserves free energy from O2 reduction into an electrochemical proton gradient by coupling the redox reaction to proton-pumping across the membrane. O2 reduction produces water at the bimetallic heme a3/CuB active site next to a hydrophobic cavity deep within the membrane. Water molecules in this cavity have been suggested to play an important role in the proton-pumping mechanism. Here, we show by molecular dynamics simulations that the conserved arginine/heme a3 delta-propionate ion pair provides a gate, which exhibits reversible thermal opening that is governed by the redox state and the water molecules in the cavity. An important role of this gate in the proton-pumping mechanism is supported by site-directed mutagenesis experiments. Transport of the product water out of the enzyme must be rigidly controlled to prevent water-mediated proton leaks that could compromise the proton-pumping function. Exit of product water is observed through the same arginine/propionate gate, which provides an explanation for the observed extraordinary spatial specificity of water expulsion from the enzyme.
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pubmed:commentsCorrections |
http://linkedlifedata.com/resource/pubmed/commentcorrection/16014708-10891065,
http://linkedlifedata.com/resource/pubmed/commentcorrection/16014708-11779547,
http://linkedlifedata.com/resource/pubmed/commentcorrection/16014708-11986647,
http://linkedlifedata.com/resource/pubmed/commentcorrection/16014708-12144789,
http://linkedlifedata.com/resource/pubmed/commentcorrection/16014708-12163075,
http://linkedlifedata.com/resource/pubmed/commentcorrection/16014708-12206898,
http://linkedlifedata.com/resource/pubmed/commentcorrection/16014708-12615353,
http://linkedlifedata.com/resource/pubmed/commentcorrection/16014708-12765763,
http://linkedlifedata.com/resource/pubmed/commentcorrection/16014708-14529616,
http://linkedlifedata.com/resource/pubmed/commentcorrection/16014708-14581193,
http://linkedlifedata.com/resource/pubmed/commentcorrection/16014708-14645061,
http://linkedlifedata.com/resource/pubmed/commentcorrection/16014708-14660787,
http://linkedlifedata.com/resource/pubmed/commentcorrection/16014708-14673090,
http://linkedlifedata.com/resource/pubmed/commentcorrection/16014708-14699047,
http://linkedlifedata.com/resource/pubmed/commentcorrection/16014708-14971958,
http://linkedlifedata.com/resource/pubmed/commentcorrection/16014708-15041635,
http://linkedlifedata.com/resource/pubmed/commentcorrection/16014708-15100038,
http://linkedlifedata.com/resource/pubmed/commentcorrection/16014708-15178480,
http://linkedlifedata.com/resource/pubmed/commentcorrection/16014708-15451676,
http://linkedlifedata.com/resource/pubmed/commentcorrection/16014708-15534221,
http://linkedlifedata.com/resource/pubmed/commentcorrection/16014708-1749933,
http://linkedlifedata.com/resource/pubmed/commentcorrection/16014708-272644,
http://linkedlifedata.com/resource/pubmed/commentcorrection/16014708-9122160,
http://linkedlifedata.com/resource/pubmed/commentcorrection/16014708-9315701,
http://linkedlifedata.com/resource/pubmed/commentcorrection/16014708-9380672,
http://linkedlifedata.com/resource/pubmed/commentcorrection/16014708-9443344,
http://linkedlifedata.com/resource/pubmed/commentcorrection/16014708-9533684,
http://linkedlifedata.com/resource/pubmed/commentcorrection/16014708-9560212,
http://linkedlifedata.com/resource/pubmed/commentcorrection/16014708-9624044,
http://linkedlifedata.com/resource/pubmed/commentcorrection/16014708-9874767,
http://linkedlifedata.com/resource/pubmed/commentcorrection/16014708-9874779
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pubmed:language |
eng
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pubmed:journal |
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pubmed:citationSubset |
IM
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pubmed:chemical |
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pubmed:status |
MEDLINE
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pubmed:month |
Jul
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pubmed:issn |
0027-8424
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pubmed:author |
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pubmed:issnType |
Print
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pubmed:day |
26
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pubmed:volume |
102
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
10478-81
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pubmed:dateRevised |
2009-11-18
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pubmed:meshHeading |
pubmed-meshheading:16014708-Animals,
pubmed-meshheading:16014708-Arginine,
pubmed-meshheading:16014708-Biological Transport,
pubmed-meshheading:16014708-Cattle,
pubmed-meshheading:16014708-Computer Simulation,
pubmed-meshheading:16014708-Electron Transport Complex IV,
pubmed-meshheading:16014708-Heme,
pubmed-meshheading:16014708-Ion Channel Gating,
pubmed-meshheading:16014708-Mutagenesis, Site-Directed,
pubmed-meshheading:16014708-Paracoccus denitrificans,
pubmed-meshheading:16014708-Propionates,
pubmed-meshheading:16014708-Proton Pumps,
pubmed-meshheading:16014708-Water
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pubmed:year |
2005
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pubmed:articleTitle |
Gating of proton and water transfer in the respiratory enzyme cytochrome c oxidase.
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pubmed:affiliation |
Helsinki Bioenergetics Group, Institute of Biotechnology, Program for Structural Biology and Biophysics, University of Helsinki, PB 65 (Viikinkaari 1), 00014 Helsinki, Finland. marten.wikstrom@helsinki.fi
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pubmed:publicationType |
Journal Article,
Comparative Study,
Research Support, Non-U.S. Gov't
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