Cited by 388Nitric Oxide and Endothelin EffectsMetal-Catalyzed Oxygenation MechanismsHemoglobin structure and function

Inducible Nitric-oxide Synthase Generates Superoxide from the Reductase Domain

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Xia, Yong, Roman, Linda J., Masters, Bettie Sue S., Zweier, Jay L.·1998·Journal of Biological Chemistry

Abstract

In the absence of L-arginine, the heme center of the oxygenase domain of neuronal nitric-oxide synthase reduces molecular oxygen to superoxide (O-2). Our recent work has provided evidence that inducible NOS (iNOS) may also catalyze O-2 formation in macrophages. However, there has been a lack of direct evidence of superoxide generation from the purified iNOS, and it was previously hypothesized that significant O-2 production does not occur. Moreover, the mechanism and enzyme site responsible for O-2 generation is unknown. To determine whether iNOS produces O-2 and to identify the mechanism of this process, we performed electron paramagnetic resonance measurements on purified iNOS using the spin trap 5,5-dimethyl-1-pyrroline N-oxide. In the presence of NADPH, prominent O-2 adduct signals were detected from iNOS. These signals were totally abolished by superoxide dismutase but not affected by catalase. High concentrations of L-arginine decreased this O-2 formation, whereas its enantiomer D-arginine did not. Pre-incubation of iNOS with the flavoprotein inhibitor diphenyleneiodonium totally blocked these O-2 signals. Conversely, pretreatment of the enzyme with the heme blocker cyanide had no effect on O-2 generation. Furthermore, strong O-2 generation was directly detected from the isolated iNOS reductase domain. Together, these data demonstrate that iNOS does generate O-2, and this mainly occurs at the flavin-binding sites of the reductase domain.

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Research works printed but not linked: 6

  1. Xia, Y., Dawson, V. L., Dawson, T. M., Snyder, S. H., and Zweier, J. L. (1996) Proc. Natl. Acad. Sci. U. S. A. 93, 6770 -6774
  2. Abu-Soud, H. M., and Stuehr D. J. (1993) Proc. Natl. Acad. Sci. U. S. A. 90, 10769 -10772
  3. Xia, Y., and Zweier, J. L. (1997) Proc. Natl. Acad. Sci. U. S. A. 94, 6954 -6958
  4. Roman, L. J., Sheta, E. A., Martasek, P., Gross, S. S., Liu, Q., and Masters, B. S. S. (1995) Proc. Natl. Acad. Sci. U. S. A. 92, 8428 -8432
  5. Bredt, D. S., and Snyder, S. H. (1989) Proc. Natl. Acad. Sci. U. S. A. 86, 9030 -9033
  6. Beckman, J. S., Beckman, T. W., Chen, J., Marshall, P. A., and Freeman, B. A. (1990) Proc. Natl. Acad. Sci. U. S. A. 87, 1620 -1624

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Authors
Xia, Y., Roman, L. J., Masters, B. S. S., & Zweier, J. L.
Affiliations
  • Johns Hopkins University (US)
  • The University of Texas at San Antonio Health Science Center (US)
Corresponding author
Zweier, Jay L.
Venue
Journal of Biological Chemistry
Publisher
Elsevier BV
Published
1998-08
Volume
273
Issue
35
Pages
22635-22639
ISSN
0021-9258 (ISSN-L)
OpenAlex
W2064619021
Cited by
388
References
29
Citations by year
2026: 1 · 2025: 3 · 2024: 2 · 2023: 7 · 2022: 2 · 2021: 8 · 2020: 7 · 2019: 5 · 2018: 9 · 2017: 10 · 2016: 9 · 2015: 6 · 2014: 12 · 2013: 18 · 2012: 14
FWCI
10.43
Type
journal article
Language
en
Open access
Locations
  • Journal of Biological Chemistry (publishedVersion, cc-by-nc-nd)
  • PubMed (publishedVersion)
Funders
  • Welch Foundation (AQ-1192)
  • American Heart Association
  • National Institutes of Health (HL38324)
  • National Heart, Lung, and Blood Institute (HL-38324, HL52315, P50HL052315)
  • National Institute of General Medical Sciences (R01GM052419, GM-52419)
Topics
  • Health Sciences › Medicine › Physiology › Nitric Oxide and Endothelin Effects
  • Physical Sciences › Chemistry › Inorganic Chemistry › Metal-Catalyzed Oxygenation Mechanisms
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cell Biology › Hemoglobin structure and function
Keywords
inducible nitric oxide synthase, superoxide production, oxygenase domain, reductase domain, flavin binding site, L-arginine, diphenyleneiodonium, flavoprotein, macrophages, spin trapping, NADPH, superoxide dismutase
MeSH terms
Animals, Catalysis, Cyclic N-Oxides, Electron Spin Resonance Spectroscopy, Oxidoreductases, Oxygenases, Recombinant Proteins, Spin Labels, Superoxides, Nitric Oxide Synthase, Mice, Nitric Oxide Synthase Type II

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