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Physicochemical characteristics of previously suggested surface-modified polymeric nanogranules (SMPN) and catalytic and stability properties of a-chymotrypsin entrapped into such nanogranules in a nonpolar solvent were investigated in more details. SMPN were obtained by polymerization of an acrylamide/N,N'-methylene-bisacrylamide mixture in a mixed reversed micellar system composed of Aerosol OT [sodium di(2-ethylhexyl)sulfosuccinate] and the polymeric surfactant Pluronic F-108 modified with polymerizable groups, followed by the chromatographic removal of the auxiliary surfactant, Aerosol OT. An optimal solvent system was found providing the required orientation of the polymeric surfactant in starting mixed micelles, i. e. with polar fragments immersed into the micellar interior and apolar fragments protruding into organic solvent. The hydrodynamic diameter of SMPN in benzene solution was estimated by means of quasi-elastic light scattering to be 84 f 1 nm. Catalytic and stability properties of a-chymotrypsin entrapped into SMPN strongly depended on conditions of preparation of SMPN. The optimal concentration of acrylamide monomers in the micellar interior and hydration degree of starting reversed micelles were found to be 20% by mass and w, = 15, respectively. a-Chymotrypsin-containing SMPN were used as a catalyst in the synthesis of N-acetyl-L-tyrosine ethyl ester from N-acetyl-L-tyrosine and ethanol, performed in a membrane reactor Biocatalysis in non-aqueous media has received growing attention during the last decade due to its obvious potentials, such as conversion of hydrophobic compounds and favorable shifts of reaction equilibrium [l, 21. One of the main problems encountered when one tries to conduct enzymic reactions in organic solvents is how to protect the biocatalyst from denaturation by such an unnatural environment. A number of approaches have been developed to overcome this obstacle [3]. Many of them are based on the simple idea that denaturation can be prevented by spatial separation of the organic solvent on a macrolevel or microlevel inside the limits of a non-aqueous reaction system. This approach is realized, for example, in systems of reversed surfactant micelles in nonpolar organic solvents [4, Abbreviations. SMPN, surface-modified polymeric nanogranules ; AOT, sodium bis(2-ethylhexyl sulfosuccinate); AcTyrEt, N-acetyl-L-tyrosine ethyl ester; AcTyr, N-acetyl-L-tyrosine; TLC, thin-layer chromatography; Pluronic F-108, poly(ethy1ene oxide)-poly(propy1ene oxide)-poly(ethy1ene oxide) triblock copolymer.Enzyme. a-Chymotrypsin (EC 3.4.21.1).in this way the unfavorable direct contact with the surrounding organic solvent is avoided. Enzyme-containing reversed micellar systems seem to be quite promising in many respects [4,5]. However, their practical application is severely restricted by considerable difficulties in enzyme and especially reactionproduct recovery caused by the presence of high concentrations of low-molecular-mass surfactants which are notoriously resistant to any separation proce...

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We propose the use of data on the topography of the label-accessible surface of a protein molecule obtained by the method of tritium planigraphy as a criterion for choosing the optimal intermediate arrangements of alpha-helices in globular proteins so as to model their three-dimensional structures. This approach has been used for modelling the three-dimensional structure of parvalbumin III from pike. The proposed model has been compared with high-resolution X-ray structural data for a related protein, paryvalbumin from carp. The possibilities and limitations of this approach are discussed.