PMID- 14766756
OWN - NLM
STAT- MEDLINE
DCOM- 20040722
LR  - 20210206
IS  - 0021-9258 (Print)
IS  - 0021-9258 (Linking)
VI  - 279
IP  - 16
DP  - 2004 Apr 16
TI  - Two sites of interaction of anions with cytochrome a in oxidized bovine 
      cytochrome c oxidase.
PG  - 16170-7
AB  - An interaction between cytochrome a in oxidized cytochrome c oxidase (CcO) and 
      anions has been characterized by EPR spectroscopy. Those anions that affect the 
      EPR g = 3 signal of cytochrome a can be divided into two groups. One group 
      consists of halides (Cl-, Br-, and I-) and induces an upfield shift of the g = 3 
      signal. Nitrogen-containing anions (CN-, NO2-, N3-, NO3-) are in the second group 
      and shift the g = 3 signal downfield. The shifts in the EPR spectrum of CcO are 
      unrelated to ligand binding to the binuclear center. The binding properties of 
      one representative from each group, azide and chloride, were characterized in 
      detail. The dependence of the shift on chloride concentration is consistent with 
      a single binding site in the isolated oxidized enzyme with a Kd of approximately 
      3 mm. In mitochondria, the apparent Kd was found to be about four times larger 
      than that of the isolated enzyme. The data indicate it is the chloride anion that 
      is bound to CcO, and there is a hydrophilic size-selective access channel to this 
      site from the cytosolic side of the mitochondrial membrane. An observed 
      competition between azide and chloride is interpreted by azide binding to three 
      sites: two that are apparent in the x-ray structure plus the chloride-binding 
      site. It is suggested that either Mg2+ or Arg-438/Arg-439 is the chloride-binding 
      site, and a mechanism for the ligand-induced shift of the g = 3 signal is 
      proposed.
FAU - Fabian, Marian
AU  - Fabian M
AD  - Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 
      77005, USA. fabian@rice.edu
FAU - Jancura, Daniel
AU  - Jancura D
FAU - Palmer, Graham
AU  - Palmer G
LA  - eng
GR  - GM 55807/GM/NIGMS NIH HHS/United States
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, P.H.S.
DEP - 20040206
PL  - United States
TA  - J Biol Chem
JT  - The Journal of biological chemistry
JID - 2985121R
RN  - 0 (Anions)
RN  - 9035-34-1 (Cytochromes a)
RN  - EC 1.9.3.1 (Electron Transport Complex IV)
SB  - IM
MH  - Animals
MH  - Anions/chemistry/metabolism
MH  - Binding Sites
MH  - Cattle
MH  - Cytochromes a/*chemistry/metabolism
MH  - Electron Spin Resonance Spectroscopy
MH  - Electron Transport Complex IV/*chemistry/metabolism
MH  - Kinetics
MH  - Oxidation-Reduction
MH  - Protein Binding
EDAT- 2004/02/10 05:00
MHDA- 2004/07/23 05:00
CRDT- 2004/02/10 05:00
PHST- 2004/02/10 05:00 [pubmed]
PHST- 2004/07/23 05:00 [medline]
PHST- 2004/02/10 05:00 [entrez]
AID - S0021-9258(20)88338-0 [pii]
AID - 10.1074/jbc.M311834200 [doi]
PST - ppublish
SO  - J Biol Chem. 2004 Apr 16;279(16):16170-7. doi: 10.1074/jbc.M311834200. Epub 2004 
      Feb 6.