Nitrous acid, reaction with nucleic acids

When oxides of nitrogen come in contact with water, both nitrous and nitric acids are formed (18) (Table IV). Toxic reactions may result from pH decrease. Other toxic reactions may be a consequence of deamination reactions with amino acids and nucleic acid bases. Another consideration is the reactions of oxides of nitrogen with double bonds (Table IV). The cis-trans isomerization of oleic acid exposed to nitrous acid has been reported (19). Furthermore, the reaction of nitrogen dioxide with unsaturated compounds has resulted in the formation of both transient and stable free radical products (20, 21) (Table V). A further possibility has been raised in that nitrite can react with secondary amines to form nitrosamines which have carcinogenic properties (22). Thus, the possible modes of toxicity for oxides of nitrogen are numerous and are not exhausted by this short list. 

FIGURE 1.8 Some chemical reactions of bases and nucleotides, (a) Hydrolysis of a dinucleotide by alkali. Bases are denoted by B1 and B2. R denotes ribose or deoxyribose. (b to k) Chemical reactions (b) bisulfite, (c) chloroacetaldehyde, (d) diethyl pyrocarbonate, (e) dimethyl sulfate, (f) formaldehyde, (g) glyoxal, (h) hydrazine, (i) nitric acid, (j) nitrous acid, and (k) osmium tetroxide. Partly from R. L. P. Adams, J. P. Knowler, and D. P. Leader (1986). In The Biochemistry of the Nucleic Acids, 10th ed., pp. 5—34. Chapman Hall, with permission. 

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