Hunting oxygen complexes of nitric oxide synthase at low temperature and high pressure
- INSERM U710, Place Eugene Bataillon, Universite Montpellier II, Montpellier (France)
- Institut fuer Pharmakologie und Toxikologie, Karl-Franzens-Universitaet Graz (Austria)
- Department of Molecular Biosciences, University of Oslo (Norway)
The reaction of nitric oxide synthase (NOS) with oxygen is fast and takes place within several steps, separated by ephemeral intermediates. The use of extreme experimental conditions, such as low temperature and high pressure, associated to rapid kinetic analysis, has proven to be a convenient tool to study this complex reaction. Stopped-flow experiments under high pressure indicated that oxygen binding occurred in more than one step. This was further corroborated by the detection of two short-lived oxy-compounds, differing in their spectral and electronic properties. Oxy-I resembles the ferrous oxygen complex known for cytochrome P450, whereas oxy-II appears to be locked in the superoxide form. Subzero temperature spectroscopy, together with an analytical separation method, revealed that the subsequent one-electron reduction of the oxygen complex is carried out by the NOS cofactor tetrahydrobiopterin (BH4). The low-temperature stabilized oxidation product of BH4 was found to be a protonated BH3 radical. Finally, work in the presence of a BH4 analog indicated that proton transfer to the activated oxygen complex is a second essential function of BH4.
- OSTI ID:
- 20793211
- Journal Information:
- Biochemical and Biophysical Research Communications, Vol. 338, Issue 1; Other Information: DOI: 10.1016/j.bbrc.2005.08.090; PII: S0006-291X(05)01802-4; Copyright (c) 2005 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0006-291X
- Country of Publication:
- United States
- Language:
- English
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