On the hydrophobicity of nitrogen dioxide: Could there be a “lens” effect for NO2 reaction kinetics?

Abstract

Solvent "lens" effects for the reaction kinetics of NO 2 can be evaluated on the basis of published Henry's law constants for nitrogen dioxide in various solvents. Water-to-organic solvent partition coefficients were derived from Henry's law constants and used to assess the tendencies of NO 2 toward fleeing the aqueous environments and concentrating in biological hydrophobic media. It is concluded, based only on the estimated aqueous medium-to-cell membrane partition coefficient for NO 2 , that such tendencies will be relatively small, and that they may account for an acceleration of chemical reactions in biological hydrophobic media with reaction kinetics that are first order on NO 2 by a factor of approximately 3 ± 1. Thus, kinetic effects due to mass action will be relatively small but it is also important to recognize that because NO 2 will tend to dissolve in cell membranes, reactions with cell membrane components will not be hindered by lack of physical solubility at these loci. In comparison to other gases, nitrogen dioxide is less hydrophobic than NO, O 2 and N 2 .

Gastric S-nitrosothiol formation drives the antihypertensive effects of oral sodium nitrite and nitrate in a rat model of renovascular hypertension

“…In addition, the simultaneous production of NO x and NO 2 x leads to N-and S-nitros(yl)ation of targets [7,27,28] within the gastric lumen[42] by either oxidative nitrosylation (NO 2 x oxidizes a target to a radical, which in turn recombines with NO x ) or N 2 O 3 nitrosation (recombination of NO x and NO 2 x to yield N 2 O 3 , which then nitrosates a target directly) [43][44][45] . In addition, both NO x and NO 2…”

Mechanisms and kinetic profiles of superoxide-stimulated nitrosative processes in cells using a diaminofluorescein probe

“…Under our experimental conditions, potential extracellular NO 2 d sources were minimized, so NO 2 d was most likely formed intracellularly via ONOO À /CO 2 decay, a process that was enhanced in the presence of CO 2 . Other ONOO À -derived species are formed, but only NO 2 d has the physical and chemical properties to cross biological membranes [46,47]. Thus, being lipid soluble and arguably the least aggressive of the ONOO À -derived radical intermediates [6], it might have a biological lifetime long enough to act in a paracrine style.…”

“…FCN is a extracellular oxidant scavenger [21,45], indicating the critical participation of a peroxynitrite-derived cell membranepermeable species in the process. Among all of these oxidant species, only peroxynitrous acid (ONOOH) and nitrogen dioxide (NO 2 d ) [46,47] are likely to freely cross biological lipid bilayers. However, the NO 2 d permeability coefficient was estimated to be 4000-fold higher than the permeability coefficient of ONOOH [46,47].…”

“…Among all of these oxidant species, only peroxynitrous acid (ONOOH) and nitrogen dioxide (NO 2 d ) [46,47] are likely to freely cross biological lipid bilayers. However, the NO 2 d permeability coefficient was estimated to be 4000-fold higher than the permeability coefficient of ONOOH [46,47]. In addition, only NO 2 d reacts directly with FCN at a significantly competitive rate constant (k ¼ 3 Â 10 6 M À 1 s À 1 ) [45]; the direct reaction of FCN and ONOO À is very slow (k ¼ 5.1 M À 1 s À 1 ) [45].…”

Development of a new Long Path Absorption Photometer (LOPAP) instrument for the sensitive detection of NO<sub>2</sub> in the atmosphere

“…in which H NO 2 is the NO 2 Henry's law constant (1.6 × 10 −2 M atm −1 at 288 K, calculated using the expression from Squadrito and Postlethwait, 2009), c is the mean thermal molecular velocity (364 m s −1 at 288 K), R is the gas constant (8.314 J M −1 K −1 ), T the temperature and D NO 2 is the aqueous phase diffusion coefficient (1.1 × 10 −5 cm 2 s −1 at 288 K, Cheung et al, 2000;Komiyama and Inoue, 1980 From the slope of the plot shown in Fig. 5 a rate coefficient k NO 2 +NEDA = (3.6 ± 1.6) × 10 6 M −1 s −1 has been determined using Eq.…”