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13C NMR of study of entrapping proteins (α-chymotrypsin) into reversed micelles of surfactants (aerosol OT) in organic solvents (n-octane)
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1989
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Reversed MicelleEngineeringOrganic SolventsBiochemistryMicelleSurfactant SolutionMolecular SimulationMolecular BiophysicsAerosol OtSolution Nmr SpectroscopyChromatographyMedicineProtein Phase SeparationBiophysicsBiomolecular EngineeringReversed MicellesEmulsion
Hydrated reversed micelles of Aerosol OT (AOT) in octane have been studied by 13 C NMR spectroscopy. The changes of spin-lattice relaxation times ( T 1 ) for individual segments of the AOT molecule, induced by entrapping a protein (α-chymotrypsin) into the micelle, have been determined by the inversion-recovery technique. The dramatic (three-fold) increase of T 1 found for the α-CH 2 groups in the AOT molecules indicates that (unlike in the unfilled micelle) in the protein-containing micelle the boundary of the water cavity is shifted outward (0.5-0.7 nm, under the given experimental conditions), the alkyl chains of the surfactant being “flooded” by water molecules. This observation explains why the outer size of the reversed micelle does not change on insertion of a bulky protein molecule.