PMID- 7926003
OWN - NLM
STAT- MEDLINE
DCOM- 19941107
LR  - 20190621
IS  - 0014-5793 (Print)
IS  - 0014-5793 (Linking)
VI  - 352
IP  - 3
DP  - 1994 Oct 3
TI  - Peroxide-induced spectral perturbations of the 280-nm absorption band of 
      cytochrome c oxidase.
PG  - 365-8
AB  - It is now widely believed that the first two electrons transferred to the 
      dioxygen reduction site in cytochrome c oxidase (CcO) are not coupled to proton 
      translocation. The activation of the pump cycle correlates with the binding of 
      dioxygen to the binuclear center. In order to investigate conformational changes 
      in CcO associated with the formation of dioxygen intermediates during the 
      catalytic cycle of CcO, the effects of hydrogen peroxide binding to CcO have been 
      examined using UV optical absorption and second derivative techniques. Our data 
      indicates that in the presence low concentrations of H2O2 (2:1 molar ratio) an 
      initial CcO-peroxide species is formed in which the 280-nm absorption band is red 
      shifted. This red shift occurs prior to spectral changes associated with H2O2 
      binding to cytochrome a3. Upon addition of higher concentrations of H2O2 (> 10 
      equivalents of H2O2 per equivalent of CcO) oxidized CcO is converted to F-state 
      enzyme with no corresponding shift at 280 nm. It is suggested that H2O2 initially 
      binds to CuB2+ resulting in a conformational change in the enzyme giving rise to 
      a red-shifted 280 nm band. The absence of any conformational changes in F-state 
      enzyme is consistent with the lack of bridging interactions with CuB2+ in this 
      intermediate.
FAU - Larsen, R W
AU  - Larsen RW
AD  - Department of Chemistry, University of Hawaii at Manoa, Honolulu 96822.
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - England
TA  - FEBS Lett
JT  - FEBS letters
JID - 0155157
RN  - BBX060AN9V (Hydrogen Peroxide)
RN  - EC 1.9.3.1 (Electron Transport Complex IV)
SB  - IM
MH  - Animals
MH  - Cattle
MH  - Electron Transport Complex IV/*chemistry/drug effects/metabolism
MH  - Hydrogen Peroxide/metabolism/*pharmacology
MH  - Oxidation-Reduction
MH  - Protein Binding
MH  - *Protein Conformation/drug effects
MH  - Spectrophotometry, Ultraviolet
EDAT- 1994/10/03 00:00
MHDA- 1994/10/03 00:01
CRDT- 1994/10/03 00:00
PHST- 1994/10/03 00:00 [pubmed]
PHST- 1994/10/03 00:01 [medline]
PHST- 1994/10/03 00:00 [entrez]
AID - 0014-5793(94)00999-6 [pii]
AID - 10.1016/0014-5793(94)00999-6 [doi]
PST - ppublish
SO  - FEBS Lett. 1994 Oct 3;352(3):365-8. doi: 10.1016/0014-5793(94)00999-6.