The synthesis of oligosaccharide-branched cyclodextrins and their interaction with concanavalin A

New oligosaccharide-branched -cyclodextrins having a various oligosaccharides in a primary hydroxyl group of -cyclodextrin(CD) were synthesized and examined for the interaction with the immobilized concanavalin A(ConA) compared with 6-O-glucosyl and maltosyl CD. Oligosaccharides were converted to lactones at the reducing end, which was connected with 6-monoamino--CD forming an amide bond. For the analysis of the interaction between ConA immobilized on an aminosilane-hydrogel surface and various oligosaccharide CDs, a biosensor of the FISONS IAsys apparatus based on a resonant mirror detector (RMD) was used. As a result, it interacted with immobilized ConA and both maltosyl--CD(3) and maltosyl--CD(6), and glucosylglucono-amide--CD(7) with the association constants, K_a of 134, 833 and 8730 M^–1, respectively.     

Microwave‐Assisted Solid‐Phase Synthesis of Antifreeze Glycopeptides

Microwave‐assisted solid‐phase synthesis allows for the rapid and large‐scale preparation and structure–activity characterization of tandem repeating glycopeptides, namely monodispersed synthetic antifreeze glycopeptides (syAFGPs, H‐[Ala‐Thr(Galβ1,3GalNAcα1→)‐Ala]_n‐OH, n=2–6). By employing novel AFGP analogues, we have demonstrated that of the monodispersed syAFGP_n (n=2–6, degree of polymerization, DP=2–6, M_w=1257–3690 Da), syAFGP₅ (DP=5, M_w=3082 Da) and syAFGP₆ (DP=6, M_w=3690 Da) exhibit the ability to form typical hexagonal bipyramidal ice crystals and satisfactory thermal hysteresis activity. Structural characterization by NMR and CD spectroscopy revealed that syAFGP₆ forms a typical poly‐L ‐proline type II helix‐like structure in aqueous solution whereas enzymatic modification by sialic acid of the residues at the C‐3 positions of the nonreducing Gal residues disturbs this conformation and eliminates the antifreeze activity.