PMID- 16274235
OWN - NLM
STAT- MEDLINE
DCOM- 20060104
LR  - 20131121
IS  - 0006-2960 (Print)
IS  - 0006-2960 (Linking)
VI  - 44
IP  - 45
DP  - 2005 Nov 15
TI  - A role for the protein in internal electron transfer to the catalytic center of 
      cytochrome c oxidase.
PG  - 14881-9
AB  - Internal electron transfer (ET) to heme a(3) during anaerobic reduction of 
      oxidized bovine heart cytochrome c oxidase (CcO) was studied under conditions 
      where heme a and Cu(A) were fully reduced by excess hexaamineruthenium. The data 
      show that ET to heme a(3) is controlled by the state of ionization of a single 
      protolytic residue with a pK(a) of 6.5 +/- 0.2. On the basis of the view that ET 
      to the catalytic site is limited by coupled proton transfer, this pK(a) was 
      attributed to Glu60 which is located at the entrance of the proton-conducting K 
      channel on the matrix side of CcO. It is proposed that Glu60 controls proton 
      entry into the channel. However, even with this channel open, there is the second 
      factor that regulates ET, and this is ascribed to the rate of proton diffusion in 
      the channel. In addition, it is concluded that proton transfer in the K channel 
      is reversibly inhibited by the detergent Triton X-100. It is also found that the 
      rate of ET to heme a(3) in the as-isolated resting enzyme and in CcO "activated" 
      by reaction of fully reduced enzyme with O(2) is the same, implying that the 
      catalytic sites of these two forms of oxidized enzyme are essentially identical.
FAU - Antalik, Marian
AU  - Antalik M
AD  - Department of Biochemistry and Cell Biology, MS 140, Rice University, 6100 Main, 
      Houston, Texas 77005, USA.
FAU - Jancura, Daniel
AU  - Jancura D
FAU - Palmer, Graham
AU  - Palmer G
FAU - Fabian, Marian
AU  - Fabian M
LA  - eng
GR  - GM 55807/GM/NIGMS NIH HHS/United States
PT  - Journal Article
PT  - Research Support, N.I.H., Extramural
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - Biochemistry
JT  - Biochemistry
JID - 0370623
RN  - 0 (Detergents)
RN  - 0 (Protons)
RN  - 18535-39-2 (heme a)
RN  - 3KX376GY7L (Glutamic Acid)
RN  - 42VZT0U6YR (Heme)
RN  - EC 1.9.3.1 (Electron Transport Complex IV)
SB  - IM
MH  - Animals
MH  - Catalytic Domain
MH  - Cattle
MH  - Detergents/chemistry
MH  - Electron Transport
MH  - Electron Transport Complex IV/*chemistry
MH  - *Electrons
MH  - Glutamic Acid/chemistry
MH  - Heme/analogs & derivatives/chemistry
MH  - Hydrogen-Ion Concentration
MH  - Ion Transport
MH  - Kinetics
MH  - Oxidation-Reduction
MH  - Protons
EDAT- 2005/11/09 09:00
MHDA- 2006/01/05 09:00
CRDT- 2005/11/09 09:00
PHST- 2005/11/09 09:00 [pubmed]
PHST- 2006/01/05 09:00 [medline]
PHST- 2005/11/09 09:00 [entrez]
AID - 10.1021/bi050824z [doi]
PST - ppublish
SO  - Biochemistry. 2005 Nov 15;44(45):14881-9. doi: 10.1021/bi050824z.