PMID- 7756261
OWN - NLM
STAT- MEDLINE
DCOM- 19950629
LR  - 20190613
IS  - 0006-2960 (Print)
IS  - 0006-2960 (Linking)
VI  - 34
IP  - 19
DP  - 1995 May 16
TI  - Electron transfer from cytochrome c to 8-azido-ATP-modified cytochrome c oxidase.
PG  - 6335-43
AB  - Bovine heart cytochrome c oxidase (CcO) has been modified by 8-azido-adenosine 
      5'-triphosphate (8-azido-ATP), and the electron-transfer activity from 
      ferrocytochrome c to the modified CcO under physiological ionic strengths has 
      been studied by the laser flash photolysis technique with 5-deazariboflavin and 
      EDTA as the electron donor. The kinetics of intermolecular electron transfer 
      between the redox protein partners was shown to be reduced significantly. In 
      addition, there is significant decrease in the binding affinity of the cytochrome 
      c to the oxidase upon 8-azido-ATP modification. The 8-azido-ATP-modified CcO 
      exhibited 50% of the intracomplex electron-transfer rate (ket) and 56% of the 
      association constant (Ka) normally observed between cytochrome c and native CcO 
      under otherwise identical conditions. Since the effective electron transfer rate 
      constant is the product of ket and Ka under nonsaturation conditions, the overall 
      electron-transfer rate has been curtailed by over a factor of 2. Similar 
      observations have been noted with the native CcO in the presence of 3 mM ATP. In 
      contrast, the redox potential of neither CuA nor cytochrome a was altered upon 
      8-azido-ATP modification or in the presence of 3 mM ATP. Also, no gross 
      structural changes at either the CuA or the cytochrome a site were noted, as 
      evidenced by a lack of any spectral perturbations in the EPR signals from both of 
      these centers. We conclude that ATP modulates the electron transfer from 
      cytochrome c to CcO by interacting with the CcO and altering allosterically the 
      docking. In this manner, ATP can affect the branching of the electron input from 
      ferrocytochrome c to cytochrome a and CuA.
FAU - Lin, J
AU  - Lin J
AD  - A. A. Noyes Laboratory of Chemical Physics, California Institute of Technology, 
      Pasadena 91125, USA.
FAU - Wu, S
AU  - Wu S
FAU - Chan, S I
AU  - Chan SI
LA  - eng
GR  - GM 22432/GM/NIGMS NIH HHS/United States
PT  - Journal Article
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - Biochemistry
JT  - Biochemistry
JID - 0370623
RN  - 0 (Affinity Labels)
RN  - 0 (Azides)
RN  - 0 (Cytochrome c Group)
RN  - 53696-59-6 (8-azidoadenosine 5'-triphosphate)
RN  - 8L70Q75FXE (Adenosine Triphosphate)
RN  - EC 1.9.3.1 (Electron Transport Complex IV)
SB  - IM
MH  - Adenosine Triphosphate/*analogs & derivatives/chemistry/*metabolism
MH  - Affinity Labels
MH  - Animals
MH  - Azides/*chemistry
MH  - Cattle
MH  - Cytochrome c Group/*metabolism
MH  - Electron Transport Complex IV/chemistry/*metabolism
MH  - In Vitro Techniques
MH  - Kinetics
MH  - Osmolar Concentration
MH  - Oxidation-Reduction
MH  - Protein Binding
EDAT- 1995/05/16 00:00
MHDA- 1995/05/16 00:01
CRDT- 1995/05/16 00:00
PHST- 1995/05/16 00:00 [pubmed]
PHST- 1995/05/16 00:01 [medline]
PHST- 1995/05/16 00:00 [entrez]
AID - 10.1021/bi00019a011 [doi]
PST - ppublish
SO  - Biochemistry. 1995 May 16;34(19):6335-43. doi: 10.1021/bi00019a011.