Accommodation of No in the Active Site of Mammalian and Bacterial Cytochrome C Oxidase Aa3.
From: Laboratoire d’Optique et Biosciences, CNRS, Ecole Polytechnique, F-91128 Palaiseau Cedex, France.
Biochimica et biophysica acta
- Publish Date: May 2007
- ISSN: 0006-3002
- Volume: 1767
- Issue: 5
- Pages: 387-92
- Medium: Print
- Language: English
- Citation (JAMA): Pilet Eric, Nitschke Wolfgang, Liebl Ursula, et al. Accommodation of No in the Active Site of Mammalian and Bacterial Cytochrome C Oxidase Aa3.. Biochim. Biophys. Acta May 2007;1767:387-92
Abstract
Following different reports on the stoichiometry and configuration of NO binding to mammalian and bacterial reduced cytochrome c oxidase aa(3) (CcO), we investigated NO binding and dynamics in the active site of beef heart CcO as a function of NO concentration, using ultrafast transient absorption and EPR spectroscopy. We find that in the physiological range only one NO molecule binds to heme a(3), and time-resolved experiments indicate that even transient binding to Cu(B) does not occur. Only at very high (approximately 2 mM) concentrations a second NO is accommodated in the active site, although in a different configuration than previously observed for CcO from Paracoccus denitrificans [E. Pilet, W. Nitschke, F. Rappaport, T. Soulimane, J.-C. Lambry, U. Liebl and M.H. Vos. Biochemistry 43 (2004) 14118-14127], where we proposed that a second NO does bind to Cu(B). In addition, in the bacterial enzyme two NO molecules can bind already at NO concentrations of approximately 1 microM. The unexpected differences highlighted in this study may relate to differences in the physiological relevance of the CcO-NO interactions in both species.
Mesh Headings (Keywords): Animals, Bacterial Proteins, Binding Sites, Cattle, Electron Spin Resonance Spectroscopy, Electron Transport Complex IV, Kinetics, Myocardium, Nitric Oxide, Protein Subunits, Pseudomonas
Check for Full Text / PubMed Unique Identifier (PMID): 17434442
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