Reduction nitrite

Heme d,6 another isobacteriochlorin, occurs as one of two cofactors in the reductase cytochrome cdj which mediates the nitrite reduction to nitrogen monoxide (NO) and from there to dinitrogen oxide (N20) in denitrifying bacteria.7... 

The ferrocene moiety is not just an innocent steric element to create a three-dimensional chiral catalyst environment. Instead, the Fe center can influence a catalytic asymmetric process by electronic interaction with the catalytic site, if the latter is directly coimected to the sandwich core. This interaction is often comparable to the stabilization of a-ferrocenylcarbocations 3 (see Sect. 1) making use of the electron-donating character of the Cp2Fe moiety, but can also be reversed by the formation of feirocenium systems thereby increasing the acidity of a directly attached Lewis acid. Alternative applications in asymmetric catalysis, for which the interaction of the Fe center and the catalytic center is less distinct, have recently been summarized in excellent extensive reviews and are outside the scope of this chapter [48, 49], Moreover, related complexes in which one Cp ring has been replaced with an ri -arene ligand, and which have, for example, been utilized as catalysts for nitrate or nitrite reduction in water [50], are not covered in this chapter. 

Gomez Arrayas R, Adrio J, Carretero JC (2006) Recent applications of chiral ferrocene ligands in asymmetric catalysis. Angew Chem Int Ed 45 7674—7715 Dai LX, Hou XL (2010) Chiral ferrocenes in asymmetric catalysis. Wiley-VCH, Weinheim Rigaut S, Delville MH, Losada J, Astrac D (2002) Water-soluble mono- and star-shaped hexanuclear functional organoiron catalysts for nitrate and nitrite reduction in water syntheses and electroanalytical study. Inorg Chim Acta 334 225-242... 

Both reactions follow simple second-order expressions with A 2(nitrate) = 2.19 + 0.13 l.mole .sec and 2(nitrite) = 0.644 + 0.010 l.mole . sec , both at 25 °C ". In the NOJ reduction, NO is considered to enter the inner sphere of the Re(V) complex rapidly to give [ReCl4(ONO)] which then breaks down to products, following an internal two-electron transfer in the slow step. By analogy, NO is considered to enter the Re(V) complex by displacing H2O rapidly in the nitrite reduction slow internal two-electron transfer to give NO" (or HNO) follows the latter is then consumed by Re(V). 

Klepper, L. " A Mode of Action of Herbicides Inhibition of the Normal Process of Nitrite Reduction", Research Bulletin 259. The Agriculture Experiment Station, University of Nebraska-Lincoln College of Agriculture Lincoln, 1974. 

The cyanobacteria Anflfcflenfl sp. strain PCC 7120 andNostoc ellipsosporum dechlorinated y-hexachloro[flflfleee]cyclohexane in the light in presence of nitrate to y-pentachlorocyclo-hexene (Figure 2.5), and to a mixture of chlorobenzenes (Kuritz and Wolk 1995). The reaction is dependent on the functioning of the nir operon involved in nitrite reduction (Kuritz et al. 1997). 

Electrochemical carboxylation of acetophenone with CO2 coupled with nitrite reduction proceeds by the controlled-potential electrolysis of CO2-saturated acetonitrile containing [Fe4S4 (SPh)4] , N02, PhCOCH3, and a dehydration... 

This process is commonly referred to as assimilatory nitrogen (nitrate or nitrite) reduction. The electrons for these reductions are supplied by half-cell oxidations involving NADPH/NADP" and NADH/NAD" (Table 7.11). All of these reactions and membrane transport processes are mediated by enzymes that are specific to the DIN species. Considerable variation exists among the phytoplankton species in their ability to produce the necessary enzymes. Since marine phytoplankton are often nitrogen limited, the quantity and type of DIN available in the water column can greatly influence overall phytoplankton abundance and species diversity. 

In summary, there is still much to understand about the nitrite reduction reaction. The crystal structures have shown how nitrite can bind to the di heme iron and protons can be provided to one of its oxygen atoms from two histidine residues. However, as yet no rapid reaction study has detected the release of product nitric oxide rather than the formation of the inhibitory dead-end ferrous di heme-NO complex. It is also not clear why the rate of interheme electron transfer is so slow over 11 A when nitrite or nitric oxide is the ligand to the d heme. 

It is remarkable that the oxidized states of the cytochromes cdi from P pantotrophus and P. aeruginosa have different structures. It is not clear at present whether one of these structures is superior for catalyzing nitrite reduction. Certainly in the P. pantotrophus enzyme the ligand switching at both ligand centers upon changing oxidation state is... 

The bis-hydroxylamine adduct [Fe (tpp)(NH20H)2] is stable at low temperatures, but decomposes to [Fe(tpp)(NO)] at room temperature. [Fe(porphyrin)(NO)] complexes can undergo one-and two-electron reduction the nature of the one-electron reduction product has been established by visible and resonance Raman spectroscopy. Reduction of [Fe(porphyrin)(NO)] complexes in the presence of phenols provides model systems for nitrite reductase conversion of coordinated nitrosyl to ammonia (assimilatory nitrite reduction), while further relevant information is available from the chemistry of [Fe (porphyrin)(N03)]. Iron porphyrin complexes with up to eight nitro substituents have been prepared and shown to catalyze oxidation of hydrocarbons by hydrogen peroxide and the hydroxylation of alkoxybenzenes. ... 

A number of studies have highlighted the possibility of the use of monometallic Pd catalyst for effective nitrate/nitrite reduction if a reducible support is selected. Epron et proposed a reaction mechanism for Pd/Ce02, (Fig. 1) in which oxygen vacancies at the Pd-support interface were active sites for the reduction of nitrate. Although the selectivity to nitrogen was poor, the... 

SiMoi2O40 Chlorate reduction Nitrite reduction 50%(v/v) dioxane-water (0.5 M H2SO4) 153b 155... 

P2Wi706iFe "(H20) H2O2 reduction Nitrite reduction Sulfate buffer (pH 3) Acetate buffer (pH 5) 94b... 

Studies with [ Cu"(H20))2Cu"2(X2Wi5 056)2] (abbreviated in the following as CU4X4W30 with X = P or As) This example is selected to compare nitrate reduction with the more classical nitrite reduction [115]. Correlatively, the study of the possible intermediate or final product in this reaction, namely nitrite, was also to be considered. 7U1 the experiments were carried out at pH = 5. 

Kucera, 1., and Skladal, P. (1990). Formation of a potent respiratory inhibitor at nitrite reduction by nitrite reductase isolated from the bacterium Paracoccus denitrificans. J. Basic Microbiol. 30, 515-522. 

It is remarkable that this enzyme can accept both O2 and nitrite as its oxidizing substrate, and in fact it was originally isolated as an oxidase rather than a nitrite reductase. Its role in nitrite reduction became clear when it was realized that its synthesis was induced only under anaerobic conditions and its oxidase activity was relatively small compared with the total O2-reducing activity of cells (Lam and Nicholas, 1969 Yamanaka, 1964 Yamanaka and Okunuki, 1963a). 

The major product of nitrite reduction is NO (Denariaz et ai, Iwasaki and Matsubara, 1972 Kakutani et al., 1981 Liu et ai, 1986 Masuko et ai, 1984 Sawada et ai, 1978 Zumft et ai, 1987) just as is the case with the cytochrome cd, type enzyme. As discussed previously in this chapter, the Cu-type enzyme from A. cycloclastes has been reported to reduce nitrite to N2O in the presence of NO (Averill and Tiedje, 1990 Jackson et ai, 1991), a catalytic capability apparently not exhibited by heme-type nitrite reductases. 

Libby, E., and Averill, B. A. (1992). Evidence that the type 2 copper centers are the site of nitrite reduction by Achromobacter cycloclastes nitrite reductase. Biochem. Biophys. Res. Commun. 187, 1529-1535. 

Shoun, H., and Tanimoto, T. (1991). Denitrification by the fungus Fusarium oxysporum and involvement of cytochrome P-450 in the respiratory nitrite reduction. J. Biol. Chem. 266, 11078-11082. 

Weeg-Aerssens, E., Tiedje, J. M., and Averill, B. A. (1988). Evidence from isotope labeling studies for a sequential mechanism for dissimilatory nitrite reduction. J. Am. Chem. Soc. 110, 6851-6856. 

Ye, R. W., Arunakumari, A., Averill, B. A., and Tiedje, J. M. (1992a). Mutants of Pseudomonas fluorescens deficient in dissimilatory nitrite reduction are also altered in nitric oxide reduction.). Bacterial. 174, 2560-2564-Ye, R. W., Averill, B. A., and Tiedje, J. M. (1992b). Characterization of Tn5 mutants deficient in dissimilatory nitrite reduction in Pseudomonas sp. strain G-179, which contains a copper nitrite reductase.). Bacteriol. 174, 6653-6658. 

Zafiriou, O. C., Hanley, Q. S., and Snyder, G. (1989). Nitric oxide and nitrous oxide production and cycling during dissimilatory nitrite reduction by Pseudomonas perfec txmuirina. J. Biol. Chem. 264, 5694-5699. 

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