Molecularly imprinted polymeric membranes were prepared from polystyrene resin bearing tetrapeptide derivatives H‐Asp(OcHex)‐Leu‐Asp(OcHex)‐Glu(OBzl)‐OCH2‐ (DLDE) consisting of D‐amino acid residues or L‐amino acid residues. The tetrapeptide derivatives were converted into chiral recognition sites by using not only an optically pure Boc‐Trp but also racemic Boc‐Trps as a print molecule. The chiral recognition ability depends on the combination of the absolute configuration of the print molecule and that of constituting amino acid residues. The membrane prepared from a DLDE derivative consisting of D‐amino acid residues and imprinted by Boc‐D‐Trp recognized the D‐isomer in preference to the corresponding L‐isomer and vice versa. In the present study, it was also made clear that racemic print molecules were effective in generating chiral recognition sites. The affinity constant of the generated chiral recognition site was determined to be 9.6 × 103 mol−1 · dm3, which was independent of the molecular imprinting conditions. Enantioselective permeation was attained by applying electrodialysis. An optimum permselectivity of 5.9, which corresponds to the adsorption selectivity, was attained.Summary of the molecularly imprinted polymeric membranes studied.magnified imageSummary of the molecularly imprinted polymeric membranes studied.

Molecularly imprinted polymeric membranes, bearing the tetrapeptide derivative H-Asp-(OcHex)-Ile-Asp(OcHex)-Glu(OBzl)-CH2-, were prepared during the membrane preparation (casting) process in the presence of print molecule Boc-L-Trp. The molecularly imprinted membranes thus obtained showed adsorption selectivity toward a print molecule family, such as L-Trp, L-Phe, L-Ala, L-Arg, and L-Glu. The tetrapeptide derivative in the molecularly imprinted membranes preferentially recognized the L-amino acid from the D-isomer. Enantioselective permeation was attained with the present membrane, and the D-isomer was permeated in preference to the L-isomer by using the concentration difference as a driving force for membrane transport. Electrodialysis of racemic amino acid showed the possibility that permselectivity directly reflects its adsorption selectivity. It was made clear that the optical resolution was attained by the molecularly imprinted polymeric membranes.

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Various oligosaccharides from hyaluronic acid, which were fluorescence-labeled and blocked by pyridylamination at the reducing terminal, were incubated as substrates or acceptors with bovine testicular hyaluronidase. Fluorescence-labeled reaction products in the reaction mixture were monitored selectively and directly by ion-spray mass spectrometry without chemical derivatization. As a result, several features of the relationship between oligosaccharides, substrates, and testicular hyaluronidase were clarified. When hexasaccharides or larger oligosaccharides having D-glucuronic acid at the nonreducing terminal were used as substrates, they were hydrolyzed sequentially to disaccharides from the nonreducing terminal, and these disaccharides were then transferred to other hexasaccharides. On the other hand, when heptasaccharides or larger oligosaccharides having N-acetyl-D-glucosamine at the nonreducing terminal were used as substrates, trisaccharides were released from the nonreducing terminal, and then also transferred to other hexasaccharides, thus forming nonasaccharides. Thus, the relationship between hydrolysis and transglycosylation reactions with testicular hyaluronidase was characterized using ion-spray mass spectrometry.