title: On the hydrophobicity of nitrogen dioxide: could there be a "lens" effect for NO(2) 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).
authors.affiliation: Department of Environmental Health Sciences, School of Public Health, University of Alabama at Birmingham, Birmingham, AL 35294-0022, USA. gsquadr@uab.edu
authors.forename: Giuseppe L
authors.initials: GL
authors.lastname: Squadrito
authors.forename: Edward M
authors.initials: EM
authors.lastname: Postlethwait
mesh_terms: D000465:Algorithms; D002462:Cell Membrane / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D008956:Models, Chemical; D009585:Nitrogen Dioxide / Q000737:chemistry* / Q000378:metabolism; D009930:Organic Chemicals / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
chemical_list: D009930:Organic Chemicals; D012997:Solvents; D014867:Water; D009585:Nitrogen Dioxide