PMID- 12797794
OWN - NLM
STAT- MEDLINE
DCOM- 20030728
LR  - 20131121
IS  - 0002-7863 (Print)
IS  - 0002-7863 (Linking)
VI  - 125
IP  - 24
DP  - 2003 Jun 18
TI  - FTIR detection of protonation/deprotonation of key carboxyl side chains caused by 
      redox change of the Cu(A)-heme a moiety and ligand dissociation from the heme 
      a3-Cu(B) center of bovine heart cytochrome c oxidase.
PG  - 7209-18
AB  - FTIR spectral changes of bovine cytochrome c oxidase (CcO) upon ligand 
      dissociation from heme a(3)() and redox change of the Cu(A)-heme a moiety 
      (Cu(A)Fe(a)()) were investigated. In a photosteady state under CW laser 
      illumination at 590 nm to carbonmonoxy CcO (CcO-CO), the C-O stretching bands due 
      to Fe(a3)()(2+)CO and Cu(B)(1+)CO were identified at 1963 and 2063 cm(-)(1), 
      respectively, for the fully reduced (FR) state 
      [(Cu(A)Fe(a)())(3+)Fe(a3)()(2+)Cu(B)(1+)] and at 1965 and 2061 cm(-)(1) for the 
      mixed valence (MV) state [(Cu(A)Fe(a)())(5+)Fe(a3)()(2+)Cu(B)(1+)] in H(2)O as 
      well as in D(2)O. For the MV state, however, another band due to Cu(B)(1+)CO was 
      found at 2040 cm(-)(1), which was distinct from the alpha/beta conformers in the 
      spectral behaviors, and therefore was assigned to the 
      (Cu(A)Fe(a)())(4+)Fe(a3)()(3+)Cu(B)(1+)CO generated by back electron transfer. 
      The FR-minus-oxidized difference spectrum in the carboxyl stretching region 
      provided two negative bands at 1749 and 1737 cm(-)(1) in H(2)O, which were 
      apparently merged into a single band with a band center at 1741 cm(-)(1) in 
      D(2)O. Comparison of these spectra with those of bacterial enzymes suggests that 
      the 1749 and 1737 cm(-)(1) bands are due to COOH groups of Glu242 and Asp51, 
      respectively. A similar difference spectrum of the carboxyl stretching region was 
      also obtained between (Cu(A)Fe(a)())(3+)Fe(a3)()(2+)Cu(B)(1+)CO and 
      (Cu(A)Fe(a)())(5+)Fe(a3)()(2+)Cu(B)(1+)CO. The results indicate that an oxidation 
      state of the (Cu(A)Fe(a)()) moiety determines the carboxyl stretching spectra. On 
      the other hand, CO-dissociated minus CO-bound difference spectra in the FR state 
      gave rise to a positive and a negative peaks at 1749 and 1741 cm(-)(1), 
      respectively, in H(2)O, but mainly a negative peak at 1735 cm(-)(1) in D(2)O. It 
      was confirmed that the absence of a positive peak is not caused by slow 
      deuteration of protein. The corresponding difference spectrum in the MV state 
      showed a significantly weaker positive peak at 1749 cm(-)(1) and an intense 
      negative peak at 1741 cm(-)(1) (1737 cm(-)(1) in D(2)O). The spectral difference 
      between the FR and MV states is explained satisfactorily by the spectral change 
      induced by the electron back flow upon CO dissociation as described above. Thus, 
      the changes of carboxyl stretching bands induced both by oxidation of 
      (Cu(A)Fe(a)()) and dissociation of CO appear at similar frequencies ( 
      approximately 1749 cm(-)(1)) but are ascribed to different carboxyl side chains.
FAU - Okuno, Daichi
AU  - Okuno D
AD  - Department of Photoscience, The Graduate University for Advanced Studies, Center 
      for Intergarative Bioscience, Okazaki National Research Institutes, Myodaiji, 
      Okazaki, 444-8585, Japan.
FAU - Iwase, Tadashi
AU  - Iwase T
FAU - Shinzawa-Itoh, Kyoko
AU  - Shinzawa-Itoh K
FAU - Yoshikawa, Shinya
AU  - Yoshikawa S
FAU - Kitagawa, Teizo
AU  - Kitagawa T
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - J Am Chem Soc
JT  - Journal of the American Chemical Society
JID - 7503056
RN  - 0 (Ligands)
RN  - 0 (Solutions)
RN  - 059QF0KO0R (Water)
RN  - 18535-39-2 (heme a)
RN  - 42VZT0U6YR (Heme)
RN  - 789U1901C5 (Copper)
RN  - EC 1.9.3.1 (Electron Transport Complex IV)
RN  - J65BV539M3 (Deuterium Oxide)
SB  - IM
MH  - Animals
MH  - Cattle
MH  - Copper/*chemistry/metabolism
MH  - Deuterium Oxide/chemistry
MH  - Electron Transport Complex IV/*chemistry/metabolism
MH  - Heme/*analogs & derivatives/*chemistry/metabolism
MH  - Hydrogen-Ion Concentration
MH  - Kinetics
MH  - Ligands
MH  - Myocardium/enzymology
MH  - Oxidation-Reduction
MH  - Solutions
MH  - Spectroscopy, Fourier Transform Infrared/methods
MH  - Water/chemistry
EDAT- 2003/06/12 05:00
MHDA- 2003/07/29 05:00
CRDT- 2003/06/12 05:00
PHST- 2003/06/12 05:00 [pubmed]
PHST- 2003/07/29 05:00 [medline]
PHST- 2003/06/12 05:00 [entrez]
AID - 10.1021/ja021302z [doi]
PST - ppublish
SO  - J Am Chem Soc. 2003 Jun 18;125(24):7209-18. doi: 10.1021/ja021302z.