Free radical nitric oxide

Li H, Raman CS, Glaser CB, Blasko E, Young TA, Parkinson JF, Whitlow M, Poulos TL. Crystal structures of zinc-free and -bound heme domain of human inducible nitric-oxide synthase. Implications for dimer stability and comparison with endothelial nitric-oxide synthase. J. Biol. Chem. 1999 274 21276-21284. Wink DA, Mitchell JB. Chemical biology of nitric oxide Insights into regulatory, cytotoxic, and cytoprotective mechanisms of nitric oxide. Free Radical Biol. Med. 1998 25 434-456. 

D. A. Wink, J. B. Mitchell, Chemical Biology of Nitric Oxide insights into Regulatory, Cytotoxic, and Cytoprotective Mechanisms of Nitric Oxide, Free Radic Biol Med 25 (1998) 434-56. 

Wink, D., and Mitchell, JB. 1998. Chemical biology of nitric oxide Insights into regulatory, cytotoxic, and cytoprotective mechanisms of nitric oxide. Free Radic Biol Med 25 434-456. 

Whether the enzyme action is a result of some type of nitroso thiol formation, the conversion of the N02 to a more reactive nitric oxide free radical (NO°) or other species is not yet established. Figure 10-23 summarizes these possible events. It should be understood that all the pieces in the puzzle are not yet in place. 

Patel RP, Gladwin MT (2004) Physiologic, pathologic and therapeutic implications for hemoglobin interactions with nitric oxide. Free Radic Biol Med 36 399-401... 

Brunelli L, Yermilov V, Beckman JS (2001) Modulation of catalase peroxidatic and catalatic activity by nitric oxide. Free Radic Biol Med 30 709-714... 

Watanabe N, Miura S, Zeki S et al. Hepatocellular oxidative DNA injury induced by macrophage-derived nitric oxide. Free Radic Biol Med 2001 30 1019-28. 

The formation of NO in the Ru(III)-EDTA catalysed oxidation of L-arginine by H2O2, which mimicked the action of nitric oxide synthases, was confirmed with an isolated nitric oxide free radical analyser. ... 

Leshem, Y.Y. and Haramaty, E. (1996) The characterization and contrasting effects of the nitric oxide free radical in vegetative stress and senescence of Pisum sativum Linn, foliage, J. Plant Physiol. 148, 258-263. 

Lundberg, J.O. Govoni, M. (2004). Inorganic nitrate is a possible source for systemic generation of nitric oxide. Free Radical Biology Medicine, 37, 395-400. 

Balcerczyk, A. Soszynski, M. Bartosz, G. On the specificity of 4-amino-5-methylamino-2, 7 -difluoro-fluorescein as a probe for nitric oxide. Free Radical Biol Med. 2005, 39, 327-335. 

Electron-spin resonance (ESR) indicated free radicals in a brown polymer (mean ca 1 kDa by field-desorption MS) from a glucose-4-chloroaniline model system.185 Such free radicals (see Chapter 2) could be a source of visible colour. Exposure of the melanoidin to nitric oxide, a radical-trapping agent, diminished the ESR signal by 48% and changed the colour to red-brown. 

The MPO-catalyzed chlorination of membranes of exogenous microorganisms (bacteria, viruses, parasites, etc.) is a powerful antimicrobial activity generated at the contact of neutrophils with the microbes. However, MPO also contributes to the pathogenesis of several inflammatory and vascular disorders by converting free amino acids to reactive aldehydes.It has been found that nitric oxide (the radical NO ) also plays a central role in these disorders. Activated MPO converts N02 into NO2CI and NO2 , both of which are able to nitrate tyrosine residues. These MPO-mediated nitrations are enhanced by fluxes of nitric oxide. 

Chemistry. Free-radical nitrations consist of rather compHcated nitration and oxidation reactions (31). When nitric acid is used in vapor-phase nitrations, the reaction of equation 5 is the main initiating step where NO2 is a free radical, either -N02 or -ON02. Temperatures of >ca 350° are required to obtain a significant amount of initiation, and equation 5 is the rate-controlling step for the overall reaction. Reactions 6 and 7 are chain-propagating steps. 

An important side reaction in all free-radical nitrations is reaction 10, in which unstable alkyl nitrites are formed (eq. 10). They decompose to form nitric oxide and alkoxy radicals (eq. 11) which form oxygenated compounds and low molecular weight alkyl radicals which can form low molecular weight nitroparaffins by reactions 7 or 9. The oxygenated hydrocarbons often react further to produce even lighter oxygenated products, carbon oxides, and water. 

Nitrogen monoxide ( nitric oxide ) is another stable free radical. Although known for hundreds of years, NO has only recently been discovered to be an extremely important biochemical messenger and moderator of so many biological processes that it might be better to ask Which ones is it not involved in ... 

Titov claims that the free radical mechanism applies for nitration of aliphatic hydrocarbons, of aromatic side chains, of olefins, and of aromatic ring carbons, if irf the latter case the nitrating agent is ca 60—70% nitric acid that is free of nitrous acid, or even more dil acid if oxides of nitrogen are present... 

A simplified experimental system results when free radical scavengers such as nitric oxide, iodine, or oxygen are added to the samples before... 

Their rates are decreased or the reactions are suppressed entirely by substances that scavenge free radicals (e.g., nitric oxide, molecular oxygen, or benzo-... 

Not all oxidants formed biolc cally have the potential to promote lipid peroxidation. The free radicals superoxide and nitric oxide [or endothelium-derived relaxing aor (EDRF)] are known to be formed in ww but are not able to initiate the peroxidation of lipids (Moncada et tU., 1991). The protonated form of the superoxide radical, the hydroperoxy radical, is capable of initiating lipid peroxidation but its low pili of 4.5 effectively precludes a major contribution under most physiological conditions, although this has been suggested (Aikens and Dix, 1991). Interestingly, the reaction product between nitric oxide and superoxide forms the powerful oxidant peroxynitrite (Equation 2.6) at a rate that is essentially difiiision controlled (Beckman eta/., 1990 Huie and Padmaja, 1993). 

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