TY  - JOUR
AU  - Nyquist, R.
AU  - Heitbrink, D.
AU  - Bolwien, C.
AU  - Wells, T. A.
AU  - Gennis, R. B.
AU  - Heberle, J.
TI  - Direct Observation of Protonation Reactions during the Catalytic Cycle of Cytochrome c Oxidase
JO  - Proceedings of the National Academy of Sciences of the United States of America
VL  - 100
SN  - 0027-8424
CY  - Washington, DC
PB  - Academy
M1  - PreJuSER-32452
SP  - 8715 - 8720
PY  - 2003
N1  - Record converted from VDB: 12.11.2012
AB  - Cytochrome c oxidase, the terminal protein in the respiratory chain, converts oxygen into water and helps generate the electrochemical gradient used in the synthesis of ATP. The catalytic action of cytochrome c oxidase involves electron transfer, proton transfer, and O2 reduction. These events trigger specific molecular changes at the active site, which, in turn, influence changes throughout the protein, including alterations of amino acid side chain orientations, hydrogen bond patterns, and protonation states. We have used IR difference spectroscopy to investigate such modulations for the functional intermediate states E, R2,Pm, and F. These spectra reveal deprotonation of its key glutamic acid E286 in the E and in the Pm states. The consecutive deprotonation and reprotonation of E286 twice within one catalytic turnover illustrates the role of this residue as a proton shuttle. In addition, the spectra point toward deprotonation of a redox-active tyrosine, plausibly Y288, in the F intermediate. Structural insights into the molecular mechanism of catalysis based on the subtle molecular changes observed with IR difference spectroscopy are discussed.
KW  - Biophysical Phenomena
KW  - Biophysics
KW  - Carbon Monoxide: chemistry
KW  - Catalysis
KW  - Electron Transport
KW  - Electron Transport Complex IV: chemistry
KW  - Electron Transport Complex IV: genetics
KW  - Electron Transport Complex IV: metabolism
KW  - Glutamic Acid: chemistry
KW  - Models, Molecular
KW  - Mutagenesis, Site-Directed
KW  - Oxidation-Reduction
KW  - Protein Conformation
KW  - Protons
KW  - Rhodobacter sphaeroides: enzymology
KW  - Rhodobacter sphaeroides: genetics
KW  - Spectrophotometry, Infrared
KW  - Protons (NLM Chemicals)
KW  - Glutamic Acid (NLM Chemicals)
KW  - Carbon Monoxide (NLM Chemicals)
KW  - Electron Transport Complex IV (NLM Chemicals)
KW  - J (WoSType)
LB  - PUB:(DE-HGF)16
C6  - pmid:12851460
C2  - pmc:PMC166378
UR  - <Go to ISI:>//WOS:000184371000024
DO  - DOI:10.1073/pnas.1530408100
UR  - https://juser.fz-juelich.de/record/32452
ER  -