Nitric oxide formation from

Scheme 7.10 P450 Cytochrome-mediated nitric oxide formation from oximes.

Nitric oxide formation from hydroxyurea requires a three-electron oxidation (Scheme 7.15) [114]. Treatment of hydroxyurea with a variety of chemical oxidants produces NO or NO-related species , including nitroxyl (HNO), and these reactions have recently been extensively reviewed [114]. Many of these reactions proceed either through the nitroxide radical (25) or a C-nitroso intermediate (26, Scheme 7.15) [114]. The remainder of the hydroxyurea molecule may decompose into formamide or carbon dioxide and ammonia, depending on the conditions and type of oxidant (one-electron vs. two electron) employed. 

Scheme 7.15 Oxidative nitric oxide formation from N-hydroxyureas.

Scheme 7.16 Mechanism of nitric oxide formation from the reaction of hydroxyurea and hemoglobin.

Turk, J., Corbett, J. A., Ramanadham, S., Bohrer, A., and McDaniel, M. L. (1993) Biochemical evidence for nitric oxide formation from streptozotocin in isolated pan creatic islets. Biochem. Biophys. Res. Commun. 197, 1458-1464. 

F.B. Jensen, Nitric oxide formation from the reaction of nitrite with carp and rabit hemoglobin at intermediate oxygen saturations. FEBS J. 275, 3375-3387 (2008)... 

The practical motivation for understanding the microscopic details of char reaction stem from questions such as How does the variability in reactivity from particle to particle and with extent of reaction affect overall carbon conversion What is the interdependence of mineral matter evolution and char reactivity, which arises from the catalytic effect of mineral matter on carbon gasification and the effects of carbon surface recession, pitting, and fragmentation on ash distribution How are sulfur capture by alkaline earth additives, nitric oxide formation from organically bound nitrogen, vaporization of mineral constituents, and carbon monoxide oxidation influenced by the localized surface and gas chemistry within pores ... 

Rees, D., Palmer, RM, Hodson, HF, and Moncada, S. 1989. A specific inhibitor of nitric oxide formation from L-arginine attenuates endothelium-dependent relaxation. Br J Pharmacol 96 418-424. 

Feelisch, M. (1991). The biochemical pathways of nitric oxide formation from nitrovasodilators Appropriate choice of exogenous NO donors and aspects of preparation and handling of aqueous NO solutions. /. Cardiovasc. Pharmacol. 17(Suppl. 3), S25-S33. 

Dicks, A., Swift, H., Williams, D., Butler, A., Alsadoni, H., Cox, B., 1996. Identification of Cu as the effective reagent in nitric oxide formation from S-nitrosothiols (RSNO). Journal of the Chemical Society, Perkin Transactions 2, 481-487. 

Williams, D.L.H., 1996. The Mechanism of Nitric Oxide Formation from S-nitrosothiols (Thi-onitrites). Chemical Communications, pp. 1085-1091. 

Fig. 11.1 Induction of the nitric oxide formation from nitrite by polyphenols in the gastric compartment.

NO synthases (NOS, L-arginine, NADPH oxygen oxi-doreductases, nitric oxide forming EC 1.14.13.39) represent a family of enzymes that catalyze the formation of nitric oxide (NO) from the amino acid L-arginine. In mammals, three isoforms of NOS have been identified. They are termed neuronal NOS (nNOS, NOS I, NOS1), inducible NOS (iNOS, NOS H, NOS2), and endothelial... 

Effects of cytokines on the formation of nitric oxide by human islets as determined by EPR spectroscopy. Human islets were treated for 18 hr with 75 U/ml lL-1, 3.5 nM TNF-a, and 750 U/ml IFN-y, the islets were then isolated, and EPR spectroscopy was performed as described previously (Corbett et al., 1993b). Cytokine induced nitric oxide formation is demonstrated by the genetation of an EPR detectable g = 2.04 iton-nitrosyl complex which is prevented by 0.5 mM NMMA. Reproduced with permission from Proc. Nall. Acad. Set. U S.A. (Corbett et al., 1993b). 

Nitric oxide generation from L-arginine and nitric oxide donors and the formation of cGMP. L-NMMA inhibits nitric oxide synthase. Some of the nitric oxide donors such as furoxans and organic nitrates and nitrites require a thiol cofactor such as cysteine or glutathione to form nitric oxide. 

The control of nitric oxide emission from a fluidized bed coal combustor has been extensively investigated and it was found that the level of nitric oxide emission was determined by the relative contribution of nitric oxide formation and reduction processes. (l.,2) There is a great need for quantitative information concerning the rate of these processes.(2)... 

Decrease in blood pressure Injection of acetylcholine causes vasodilation and the lowering of blood pressure. Although no innervation of the vasculature by the parasympathetic system exists, there are cholinergic receptors on the blood vessels that respond by causing vasodilation. The vasodilation is due to an acetylcholine-induced rise in intracellular Ca++—caused by the phosphatidylinositol system—that results in the formation of nitric oxide (NO) from arginine in endothelial cells.2 [Note NO is also known as endothelium-derived relaxing factor (EDRF).] (See p. 176 for more detail on nitric oxide.) In the absence of adminis-... 

From the view-point of determination of recombination rate coefficients using measurements of H atom concentrations for example, the overshoot phenomena mentioned do not invalidate the p.e. approach, since the concentrations of the overshooting species are too low to contribute to the overall radical concentrations in the recombination region. It is more likely that the conditions in many actual flames are such that the p.e. assumption will predict slightly too rapid a recombination rate from a given set of rate coefficients. In some circumstances, however, O atom overshoot may influence the accuracy of prediction of rates of O atom reactions in flames using the p.e. assumptions. This may need careful consideration, for example, before attempting to calculate nitric oxide formation by the Zeldovich mechanism. 

The first estimate of kinetic parameters for the thermal decomposition of nitric oxide were made by Zeldovich and Frank-Kamenetsky . From a study of nitric oxide formation in H2-O2-N2 flames these workers proposed a value of 82+10 kcal. mole for the activation energy of decomposition. Vetter studied the reaction over the temperature range 1200-1900 K. He found a small rate increase on addition of oxygen and postulated a chain process involving the reactions... 

Chemical absorption in scrubbers, which employ any of water, nitric acid, alkaline solutions, or solutions of urea in water can reduce tail gas NOx concentrations to below 200 ppm [55]. Physical adsorption on molecular sieves is also a feasible control method. Activated carbon cannot be used because of oxidation hazards. Chemical and physical adsorption were improved if both nitric oxide and nitrogen dioxide were present in the tail gas rather than just nitric oxide, perhaps from the formation of dinitrogen trioxide (N2O3). An advantage of any absorption or adsorption system is that the NOx collected is recovered in some form. 

Bush, P. A., Gonzalez, N. E., Griscavage, J. M., and Ignarro, L. J. (1992a). Nitric oxide synthase from cerebellum catalyzes the formation of equimolar quantities of nitric oxide and citrulline from L-arginine. Biochem. Biophys. Res. Commun. 185, 960-966. 

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