PMID- 21745457
OWN - NLM
STAT- MEDLINE
DCOM- 20111103
LR  - 20161126
IS  - 0006-3002 (Print)
IS  - 0006-3002 (Linking)
VI  - 1807
IP  - 10
DP  - 2011 Oct
TI  - A theoretical investigation of the functional role of the axial methionine ligand 
      of the Cu(A) site in cytochrome c oxidase.
PG  - 1314-27
LID - 10.1016/j.bbabio.2011.06.014 [doi]
AB  - The functional roles of the amino acid residues of the Cu(A) site in bovine 
      cytochrome c oxidase (CcO) were investigated by utilizing hybrid quantum 
      mechanics (QM)/molecular mechanics (MM) calculations. The energy levels of the 
      molecular orbitals (MOs) involving Cu d(zx) orbitals unexpectedly increased, as 
      compared with those found previously with a simplified model system lacking the 
      axial Met residue (i.e., Cu(2)S(2)N(2)). This elevation of MO energies stemmed 
      from the formation of the anti-bonding orbitals, which are generated by 
      hybridization between the d(zx) orbitals of Cu ions and the p-orbitals of the S 
      and O atoms of the axial ligands. To clarify the roles of the axial Met ligand, 
      the inner-sphere reorganization energies of the Cu(A) site were computed, with 
      the Met residue assigned to either the QM or MM region. The reorganization energy 
      slightly increased when the Met residue was excluded from the QM region. The 
      existing experimental data and the present structural modeling study also 
      suggested that the axial Met residue moderately increased the redox potential of 
      the Cu(A) site. Thus, the role of the Met may be to regulate the electron 
      transfer rate through the fine modulation of the electronic structure of the 
      Cu(A) "platform", created by two Cys/His residues coordinated to the Cu ions. 
      This regulation would provide the optimum redox potential/reorganization energy 
      of the Cu(A) site, and thereby facilitate the subsequent cooperative reactions, 
      such as the proton pump and the enzymatic activity, of CcO. This article is part 
      of a Special Issue entitled: Allosteric cooperativity in respiratory proteins.
CI  - Copyright (c) 2011 Elsevier B.V. All rights reserved.
FAU - Kang, Jiyoung
AU  - Kang J
AD  - University of Tsukuba, Tsukuba Science City, Ibaraki, Japan.
FAU - Kino, Hiori
AU  - Kino H
FAU - Tateno, Masaru
AU  - Tateno M
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20110630
PL  - Netherlands
TA  - Biochim Biophys Acta
JT  - Biochimica et biophysica acta
JID - 0217513
RN  - 0 (Ligands)
RN  - 789U1901C5 (Copper)
RN  - AE28F7PNPL (Methionine)
RN  - EC 1.9.3.1 (Electron Transport Complex IV)
SB  - IM
MH  - Amino Acid Sequence
MH  - Animals
MH  - Binding Sites/genetics
MH  - Cattle
MH  - Computational Biology/methods
MH  - Copper/*chemistry/metabolism
MH  - Electron Transport
MH  - Electron Transport Complex IV/*chemistry/genetics/metabolism
MH  - Ligands
MH  - Methionine/*chemistry/genetics/metabolism
MH  - Models, Chemical
MH  - Models, Molecular
MH  - Molecular Sequence Data
MH  - Mutation
MH  - Oxidation-Reduction
MH  - *Protein Structure, Tertiary
MH  - Quantum Theory
MH  - Sequence Homology, Amino Acid
MH  - Thermodynamics
EDAT- 2011/07/13 06:00
MHDA- 2011/11/04 06:00
CRDT- 2011/07/13 06:00
PHST- 2011/02/07 00:00 [received]
PHST- 2011/05/29 00:00 [revised]
PHST- 2011/06/22 00:00 [accepted]
PHST- 2011/07/13 06:00 [entrez]
PHST- 2011/07/13 06:00 [pubmed]
PHST- 2011/11/04 06:00 [medline]
AID - S0005-2728(11)00156-3 [pii]
AID - 10.1016/j.bbabio.2011.06.014 [doi]
PST - ppublish
SO  - Biochim Biophys Acta. 2011 Oct;1807(10):1314-27. doi: 
      10.1016/j.bbabio.2011.06.014. Epub 2011 Jun 30.