PMID- 15100053
OWN - NLM
STAT- MEDLINE
DCOM- 20040617
LR  - 20161126
IS  - 0006-3002 (Print)
IS  - 0006-3002 (Linking)
VI  - 1655
IP  - 1-3
DP  - 2004 Apr 12
TI  - Tryptophan or tyrosine? On the nature of the amino acid radical formed following 
      hydrogen peroxide treatment of cytochrome c oxidase.
PG  - 372-80
AB  - It has been reported that different amino acid radicals are formed following the 
      addition of hydrogen peroxide to cytochrome c oxidase (CcO) from bovine heart or 
      from Paracoccus denitrificans. A broad unresolved signal in the electron 
      paramagnetic resonance (EPR) spectra of bovine CcO has been assigned to a 
      tryptophan radical, probably Trp126 [Rigby et al. Biochemistry 2000, 39, 
      5921-5928]. In the P. denitrificans enzyme, a similarly broad signal but with a 
      well-resolved hyperfine structure was shown to originate from a tyrosyl radical 
      and was tentatively assigned to the active site Tyr280 [MacMillan et al. 
      Biochemistry 1999, 38, 9179-9184]. We confirm that the EPR signal from P. 
      denitrificans CcO can be simulated using spectral parameters typical for known 
      Tyr radicals in other systems. However, the rotational conformation of the 
      phenolic ring of Tyr280 is inconsistent with our simulation. Instead, the 
      simulation parameters we used correspond to the rotational conformation of ring 
      that matches very accurately the conformation found in Tyr167, a residue that is 
      close enough ( approximately 10 A) to the binuclear centre to readily donate an 
      electron. The broad unresolved EPR signal in the bovine oxidase has been thought 
      previously to be inconsistent with a tyrosyl radical. However, we have simulated 
      a hypothetical EPR spectrum arising from a Tyr129 radical (the equivalent of 
      Tyr167 in P. denitrificans CcO) and showed that it is similar to the observed 
      broad signal. The possibility exists, therefore, that the homological tyrosine 
      amino acid (Tyr167/Tyr129) is responsible for the EPR spectrum in both the 
      Paraccoccus and the bovine enzyme. This correspondence between the two enzymes at 
      least allows the possibility that this radical may have functional importance.
FAU - Svistunenko, Dimitri A
AU  - Svistunenko DA
AD  - Department of Biological Sciences, University of Essex, Wivenhoe Park, 
      Colchester, Essex CO4 3SQ, UK. svist@essex.ac.uk
FAU - Wilson, Mike T
AU  - Wilson MT
FAU - Cooper, Chris E
AU  - Cooper CE
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Review
PL  - Netherlands
TA  - Biochim Biophys Acta
JT  - Biochimica et biophysica acta
JID - 0217513
RN  - 0 (Free Radicals)
RN  - 42HK56048U (Tyrosine)
RN  - 8DUH1N11BX (Tryptophan)
RN  - BBX060AN9V (Hydrogen Peroxide)
RN  - EC 1.9.3.1 (Electron Transport Complex IV)
SB  - IM
MH  - Animals
MH  - Cattle
MH  - Electron Spin Resonance Spectroscopy
MH  - Electron Transport Complex IV/*chemistry
MH  - Free Radicals/chemistry
MH  - Hydrogen Peroxide/*pharmacology
MH  - In Vitro Techniques
MH  - Models, Molecular
MH  - Myocardium/enzymology
MH  - Paracoccus denitrificans/enzymology
MH  - Protein Conformation
MH  - Tryptophan/*chemistry
MH  - Tyrosine/*chemistry
RF  - 43
EDAT- 2004/04/22 05:00
MHDA- 2004/06/18 05:00
CRDT- 2004/04/22 05:00
PHST- 2003/03/13 00:00 [received]
PHST- 2003/06/24 00:00 [accepted]
PHST- 2004/04/22 05:00 [pubmed]
PHST- 2004/06/18 05:00 [medline]
PHST- 2004/04/22 05:00 [entrez]
AID - S0005272803002044 [pii]
AID - 10.1016/j.bbabio.2003.06.006 [doi]
PST - ppublish
SO  - Biochim Biophys Acta. 2004 Apr 12;1655(1-3):372-80. doi: 
      10.1016/j.bbabio.2003.06.006.