PMID- 10455126
OWN - NLM
STAT- MEDLINE
DCOM- 19990930
LR  - 20210209
IS  - 0021-9258 (Print)
IS  - 0021-9258 (Linking)
VI  - 274
IP  - 35
DP  - 1999 Aug 27
TI  - Electron spin resonance investigation of the cyanyl and azidyl radical formation 
      by cytochrome c oxidase.
PG  - 24611-6
AB  - Cyanide (CN(-)) is a frequently used inhibitor of mitochondrial respiration due 
      to its binding to the ferric heme a(3) of cytochrome c oxidase (CcO). As-isolated 
      CcO oxidized cyanide to the cyanyl radical ((.)CN) that was detected, using the 
      ESR spin-trapping technique, as the 5,5-dimethyl-1-pyrroline N-oxide (DMPO)/(.)CN 
      radical adduct. The enzymatic conversion of cyanide to the cyanyl radical by CcO 
      was time-dependent but not affected by azide (N(3)(-)). The small but variable 
      amounts of compound P present in the as-isolated CcO accounted for this 
      one-electron oxidation of cyanide to the cyanyl radical. In contrast, as-isolated 
      CcO exhibited little ability to catalyze the oxidation of azide, presumably 
      because of azide's lower affinity for the CcO. However, the DMPO/(.)N(3) radical 
      adduct was readily detected when H(2)O(2) was included in the system. The results 
      presented here indicate the need to re-evaluate oxidative stress in mitochondria 
      "chemical hypoxia" induced by cyanide or azide to account for the presence of 
      highly reactive free radicals.
FAU - Chen, Y R
AU  - Chen YR
AD  - Laboratory of Pharmacology and Chemistry, NIEHS, National Institutes of Health, 
      Research Triangle Park, North Carolina 27709, USA. chen6@niehs.nih.gov
FAU - Sturgeon, B E
AU  - Sturgeon BE
FAU - Gunther, M R
AU  - Gunther MR
FAU - Mason, R P
AU  - Mason RP
LA  - eng
PT  - Journal Article
PL  - United States
TA  - J Biol Chem
JT  - The Journal of biological chemistry
JID - 2985121R
RN  - 0 (Azides)
RN  - 0 (Cyanides)
RN  - 0 (Cyclic N-Oxides)
RN  - 0 (Free Radicals)
RN  - 0 (Spin Labels)
RN  - 55482-03-6 (2,2-dimethyl-5-hydroxy-1-pyrrolidinyloxy)
RN  - BBX060AN9V (Hydrogen Peroxide)
RN  - EC 1.9.3.1 (Electron Transport Complex IV)
SB  - IM
MH  - Animals
MH  - Azides/*chemistry
MH  - Cattle
MH  - Computer Simulation
MH  - Cyanides/*chemistry
MH  - Cyclic N-Oxides/chemistry
MH  - Electron Spin Resonance Spectroscopy
MH  - Electron Transport Complex IV/*chemistry
MH  - Free Radicals/chemistry
MH  - Hydrogen Peroxide/chemistry
MH  - Mitochondria, Heart/enzymology
MH  - Spin Labels
MH  - Spin Trapping
MH  - Time Factors
EDAT- 1999/08/24 00:00
MHDA- 1999/08/24 00:01
CRDT- 1999/08/24 00:00
PHST- 1999/08/24 00:00 [pubmed]
PHST- 1999/08/24 00:01 [medline]
PHST- 1999/08/24 00:00 [entrez]
AID - S0021-9258(19)55392-3 [pii]
AID - 10.1074/jbc.274.35.24611 [doi]
PST - ppublish
SO  - J Biol Chem. 1999 Aug 27;274(35):24611-6. doi: 10.1074/jbc.274.35.24611.