Ozonation of lysozyme in the presence of oleate in reverse micelles of sodium di-2-ethylhexylsulfosuccinate.

Ozone is shown to react with lysozyme in reverse micelles formed by 0.1 M sodium di-2-ethylhexylsulfosuccinate and 1.2-3 M water (pH 7.4) in isooctane solvent. The reaction of ozone is assessed by the oxidation of tryptophan residues in the protein to N-formylkynurenine. Cosolubilization of oleate in lysozyme-containing reverse micellar solutions at concentrations of 0.5-10 mM results in a progressive inhibition (19% to 82%) of the oxidation of tryptophan residues with a concentration for 50% inhibition around 2 mM. At this concentration of oleate, the magnitude of inhibition is independent of the micelle size and concentration, the overall interfacial area of reverse micelles, and the amount of ozone employed. These findings are discussed in terms of competitive reactions of ozone with unsaturated fatty acids and proteins in the lung lining fluid and in biological membranes.