Nitrogen, biochemical reactivity

Wiseman H, Halliwell B. Damage to DNA by reactive oxygen and nitrogen species role in inflammatory disease and progression to cancer. Biochem. J. 313, 17-29, 1996. 

Eu JP, Xu L, Stamler JS, Meissner G. 1999. Regulation of ryanodine receptors by reactive nitrogen species. Biochem Pharmacol 57 1079-84. 

These workers showed that dissolved arsenic and antimony in natural waters can exist in die trivalent and pentavalent oxidation states, and the biochemical and geochemical reactivities of these elements are dependent upon their chemical forms. They developed a method for the simultaneous determination of arsenic (III)+antimony (III+V)+ antimony (III+V) that uses selective hydride generation, liquid nitrogen cooled trapping, and gas chromatography-photoionisation detection. The detection limit for arsenic is lOpmol L 1 while that for antimony is 3.3pmol L 1 precision (as relative standard deviation) for both elements is better than 3%. 

More recently, Porta and co-workers [6] applied similar considerations of the polar effects to a new one-pot multicomponent process for the addition of nucleophilic radicals to aldimines, generated in situ in the presence of Ti(IV). In analogy with the Minisci reaction, Ti(IV), which acts as a Lewis acid, coordinates the nitrogen of the imine, strongly increasing the electron-deficient character of the carbon in the a-posilion and thus the reactivity of the imine toward nucleophilic radicals. This reaction, as well as the Minisci one, represents a useful route for the synthesis of a variety of poly-functionalized derivatives of chemical and biochemical relevance. 

Amato, M. and Ladd, J. N. (1988). Assay for microbial biomass based on ninhy-drin-reactive nitrogen in extracts of fumigated soils. Soil Biol. Biochem. 20, 107-114. 

Joergensen, R. G. and Brookes, P. C. (1990). Ninhydrin-reactive nitrogen measurements of microbial biomass in 0.5 M K2S04 soil extracts. Soil Biol. Biochem. 22, 1023-1027. 

P.C. Dedon et al., Reactive nitrogen species in the chemical biology of inflammation. Arch. Biochem. Biophys. 423, 12-22 (2004)... 

The key to chemical reactions, including terran biochemical reactions, at standard temperatures and pressures is the reactivity of carbon-carbon and carbon-hydrogen bonds in molecules that also contain carbon-heteroatom (any atom other than carbon or hydrogen) bonds. Bonds to heteroatoms are often said to activate carbon-carbon and carbon-hydrogen bonds. In terran metabolism, the most important heteroatoms are oxygen and nitrogen, although sulfur is also important, and other heteroatoms such as phosphorus occasionally play a role. 

Chapters 2 and 3, both authored by Wilhelm Flitsch (Federal Republic of Germany), deal, respectively, with the chemistry of the azaazulenes (not previously covered since 1958) and of hydrogenated porphyrins, a class of increasing importance in biochemical processes. The reactivity of ring-nitrogen atoms in azines toward electrophiles is covered by M. R. Grimmett (New Zealand) and B. R. T. Keene (England) in Chapter 4. 

VOCs react readily with nitrogen oxides especially imder favorable atmospheric conditions (intensive srmlight, high humidity, oxygenation, presence of transition metal species, etc.). To date, only few of the reactions are recognized, but the results of extensive studies focusing on the reactivity between NOa and the VOC parent compoimds in various biochemical systems are accessible and may be useful in solving environmental problems thus, the most relevant of these experiences are presented in this chapter. 

The first of these formulae seems less suitable than the second for these war gases, which like the mono- and di-halogenated derivatives of acetylene (see p. 45), have properties more in keeping with the presence of a divalent carbon atom. It may be concluded that it is the presence of this divalent carbon atom rather than that of the nitrogen atom which accounts for the toxicity of this radicle. The bivalent carbon atom has in fact great chemical reactivity and is the point of attack in all chemical and biochemical reactions. 

Van der Vliet, Eiserich JP, O Neill A, Halliwell B. Cross C E. Tyrosine modification by reactive, nitrogen species a closer look. Arch Biochem Biophys 1995 319 341-9. 

By virtue of unoccupied d-orbitals, iron binds to many ligands - preferably to their oxygen, nitrogen, and sulfur atoms. In enzymes and other metalloproteins, iron participates in a large number of biochemical reactions. Its chemical reactivity changes due to the oxidation state, electron spin state and redox potential, the latter ranging from +1000 mV in some heme proteins to —550 mV in some bacterial ferredoxins (Cammack et al. 1990). 

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