title: Nitrogen dioxide solubility and permeation in lipid membranes.
abstract: Nitrogen dioxide (()NO(2)) is an important oxidant molecule in biology that is produced by several biological processes, and it is also an important air pollutant. It can oxidize proteins and lipids with important consequences on their biological functions. Despite its relevance, the interaction of ()NO(2) with the cell barrier, the lipid membrane, is poorly understood. For instance, can lipid membranes limit ()NO(2) diffusion? To estimate the permeability of lipid membranes to ()NO(2) it is necessary to learn more about its solubility in the lipid phase. However, experimental data on ()NO(2) solubility is very limited. To improve our knowledge on this matter, we used a mixed approach consisting in calculating the solubility of ()NO(2) and related diatomic and triatomic gases (()NO, O(2), CO(2), etc.) in different solvents using quantum calculations and Tomasi's Polarizable Continuum Model and validating and correcting these results using experimental data available for the related gases. This approach led to an estimated partition coefficient for ()NO(2) of 2.7 between n-octanol and water, and 1.5 between lipid membranes and water, meaning that ()NO(2) is a moderately hydrophobic molecule (less than ()NO, more than CO(2)). Based on the solubility-diffusion permeability theory, the permeability coefficient was estimated to be 5 cms(-1), up to 4000 times higher than that of peroxynitrous acid. It is concluded that lipid membranes are not significant barriers to ()NO(2) transport.
authors.affiliation: Laboratorio de Química Teórica y Computacional, Universidad de la República, Iguá, Montevideo, Uruguay. ssignorelli@fcien.edu.uy
authors.forename: Santiago
authors.initials: S
authors.lastname: Signorelli
authors.forename: Matías N
authors.initials: MN
authors.lastname: Möller
authors.forename: E Laura
authors.initials: EL
authors.lastname: Coitiño
authors.forename: Ana
authors.initials: A
authors.lastname: Denicola
mesh_terms: D000393:Air Pollutants / Q000378:metabolism; D000818:Animals; D005740:Gases / Q000378:metabolism; D066298:In Vitro Techniques; D008563:Membrane Lipids / Q000378:metabolism*; D008954:Models, Biological; D009574:Nitro Compounds / Q000737:chemistry / Q000378:metabolism; D009585:Nitrogen Dioxide / Q000378:metabolism*; D010539:Permeability; D030421:Peroxynitrous Acid / Q000378:metabolism; D026361:Reactive Nitrogen Species / Q000378:metabolism; D012995:Solubility; D012997:Solvents; D013816:Thermodynamics; D014443:Tyrosine / Q000737:chemistry / Q000378:metabolism
chemical_list: D000393:Air Pollutants; D005740:Gases; D008563:Membrane Lipids; D009574:Nitro Compounds; D026361:Reactive Nitrogen Species; D012997:Solvents; D030421:Peroxynitrous Acid; D014443:Tyrosine; D009585:Nitrogen Dioxide