PMID- 16851400
OWN - NLM
STAT- MEDLINE
DCOM- 20070627
LR  - 20131121
IS  - 1520-6106 (Print)
IS  - 1520-5207 (Linking)
VI  - 109
IP  - 8
DP  - 2005 Mar 3
TI  - DFT/electrostatic calculations of pK(a) values in cytochrome c oxidase.
PG  - 3616-26
AB  - Using classical electrostatic calculations, earlier we examined the dependence of 
      the protonation state of bovine cytochrome c oxidase (CcO) on its redox state. 
      Based on these calculations, we have proposed a model of CcO proton pumping that 
      involves His291, one of the Cu(B) histidine ligands, which was found to respond 
      to redox changes of the enzyme Fe(a)(3)-Cu(B) catalytic center. In this work, we 
      employ combined density functional and continuum electrostatic calculations to 
      evaluate the pK(a)() values of His291 and Glu242, two key residues of the model. 
      The pK(a) values are calculated for different redox states of the enzyme, and the 
      influence of different factors on the pK(a)'s is analyzed in detail. The 
      calculated pK(a)() values of Glu242 are between 9.4 and 12.0, depending on the 
      redox state of the protein, which is in excellent agreement with recent 
      experimental measurements. Assuming the reduced state of heme a(3), His291 of the 
      oxidized Cu(B) center possesses a pK(a)() between 2.1 and 4.0, while His291 of 
      the reduced Cu(B) center has a pK(a) above 17. The obtained results support the 
      proposal that the His291 ligand of the Cu(B) center in CcO is a proton pump 
      element.
FAU - Popovic, Dragan M
AU  - Popovic DM
AD  - Department of Chemistry, University of California, One Shields Avenue, Davis, 
      California 95616, USA.
FAU - Quenneville, Jason
AU  - Quenneville J
FAU - Stuchebrukhov, Alexei A
AU  - Stuchebrukhov AA
LA  - eng
GR  - GM54052/GM/NIGMS NIH HHS/United States
PT  - Journal Article
PT  - Research Support, N.I.H., Extramural
PT  - Research Support, U.S. Gov't, Non-P.H.S.
PL  - United States
TA  - J Phys Chem B
JT  - The journal of physical chemistry. B
JID - 101157530
RN  - 0 (Ligands)
RN  - 0 (Protons)
RN  - 4QD397987E (Histidine)
RN  - 789U1901C5 (Copper)
RN  - EC 1.9.3.1 (Electron Transport Complex IV)
SB  - IM
MH  - Animals
MH  - Cattle
MH  - Chemistry, Physical/*methods
MH  - Copper/chemistry
MH  - Electron Transport Complex IV/*chemistry
MH  - Histidine/chemistry
MH  - Hydrogen-Ion Concentration
MH  - Ligands
MH  - Models, Chemical
MH  - Models, Molecular
MH  - Oxidation-Reduction
MH  - Protons
MH  - Software
MH  - Static Electricity
MH  - Thermodynamics
EDAT- 2006/07/21 09:00
MHDA- 2007/06/28 09:00
CRDT- 2006/07/21 09:00
PHST- 2006/07/21 09:00 [pubmed]
PHST- 2007/06/28 09:00 [medline]
PHST- 2006/07/21 09:00 [entrez]
AID - 10.1021/jp046535m [doi]
PST - ppublish
SO  - J Phys Chem B. 2005 Mar 3;109(8):3616-26. doi: 10.1021/jp046535m.