al.
(1) showed that halothane interacted with SDS micelles Volatile anesthetics are uncharged dipolar molecules with hyat the interfacial region, although the exact depth of anesthedrophobic and hydrophilic groups. Due to amphiphilicity, these tic penetration into the SDS core was not established. molecules reside at the water-macromolecule interfaces. The ex-Sodium dodecyl sulfate (SDS) micelles show four kinds tent of penetration into the hydrophobic core of macromolecules of proton peaks in the 1 H NMR frequency domain. We desighas not been established. This study measured the residence site nate the four proton peaks as a, b, methylene -(CH 2 ) 9 -, of halothane molecules in sodium dodecyl sulfate (SDS) micelles and methyl protons, starting from the hydrophilic side. Yoby 19 F and 1 H NMR. The proton peaks of SDS in the frequency shino et al. (2) showed by spin-lattice relaxation rate of domain shift by micellization. The change in the chemical shift, 19 F NMR and by equilibrium gas chromatography that the Dd, by micellization varies with the position of the proton. The values for methyl, -(CH 2 ) 9 -, b, and a protons were respectively free energies of the transfer of halothane (2-chloro-2-bromo-07.04, 06.02, 01.62, and /4.96 ppm. Addition of halothane to 1,1,1-trifluoroethane) from water to SDS micelles differed micelles dose-dependently shifted all proton peaks of SDS to a between high and low concentration ranges. Below the halolower magnetic field. The plot between Dd hal (d micelle 0 d halothane )
thane/SDS mole ratio 0.5, the interaction was characterized and halothane concentration consisted of two linear parts with a by the Langmuir adsorption isotherms with saturation kinetbreak at the halothane/SDS mole ratio of 0.5. The nuclear Overics. Above this ratio, the binding suddenly increased to hauser effect, NOE, was estimated by (1) irradiating with halohigher saturation level. thane 19 F and measuring SDS proton signals, 1 H{ 19 F}, and (2) To examine the mechanism of the two different modes of irradiating with proton signals of a and b protons and measuring anesthetic interaction with macromolecules and to character-19 F, 19 F{ 1 H}. It was found that halothane effects were confined to ize the exact binding sites of halothane on SDS micelles at the a and b positions. The decoupled signal of the halothane a microscopic level, the present study used 19 F and 1 H NMR proton in 1 H{ 19 F} NOE was a single peak when the halothane/SDS mole ratio was below 0.5. Above this ratio, a shoulder appeared. chemical shift and nuclear Overhauser effect (NOE). The Gaussian deconvolution showed that 60% of the total halothane NOE study consisted of two parts: (1) irradiating with the molecules in the micelle were restricted to the a position and 40% 19 F signal of halothane and analyzing the 1 H signal of a to the b position at saturating halothane concentrations. Haloand b protons, 1 H{ 19 F}, and (2) irradiating the halothanethane did not penetrate into the hydrophobic core. At clinical micelle solution by 1 H of a and b protons and analyzing concentrations, halothane molecules stayed at the outermost layer the 19 F response of halothane, 19 F{ 1 H}. It will be shown of hydrocarbons.