Collect. Czech. Chem. Commun. 1989, 54, 1126-1134

13C NMR of study of entrapping proteins (α-chymotrypsin) into reversed micelles of surfactants (aerosol OT) in organic solvents (n-octane)

Yurii E. Shapiroa, Nikolai A. Budanova, Andrei V. Levashovb, Nataliya L. Klyachkob, Yurii L. Khmelnitskyc and Karel Martinekd

a Polytechnic Institute, SU-150 053 Yaroslavl, U.S.S.R.
b Moscow State University, Chemistry Department, SU-117 234 Moscow, U.S.S.R.
c Institute of Biochemistry, U.S.S.R. Academy of Sciences, SU-117 071 Moscow, U.S.S.R.
d Institute of Organic Chemistry and Biochemistry, Czechoslovak Academy of Sciences, 166 10 Prague 6, Czechoslovakia


Hydrated reversed micelles of Aerosol OT (AOT) in octane have been studied by 13C NMR spectroscopy. The changes of spin-lattice relaxation times (T1) 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 T1 found for the α-CH2 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.