Semisynthesis of Complex-Type Biantennary Oligosaccharides Containing Lactosamine Repeating Units from a Biantennary Oligosaccharide Isolated from a Natural Source

Poly-<i>N</i>-acetyllactosamine (poly-LacNAc) structures on glycoproteins play important roles in essential biological events such as cell–cell adhesion. Here, we report a new strategy for the semisynthesis of LacNAc-extended complex-type biantennary oligosaccharides. We found an efficient isopropylidenation reaction that selectively protects the terminal Gal-3,4-OH of a biantennary complex-type nonasaccharide isolated from a natural source. This finding enabled the conversion of the nonasaccharide into the two types of oligosaccharides containing di-LacNAc units at one or two antennae via ten-step chemical sequences

Substrate Recognition of Glycoprotein Folding Sensor UGGT Analyzed by Site-Specifically ¹⁵N‑Labeled Glycopeptide and Small Glycopeptide Library Prepared by Parallel Native Chemical Ligation

UDP-glucose:glycoprotein glucosyltransferase (UGGT) distinguishes glycoproteins in non-native conformations from those in native conformations and glucosylates from only non-native glycoproteins. To analyze how UGGT recognizes non-native glycoproteins, we chemically synthesized site-specifically ¹⁵N-labeled interleukin 8 (IL-8) C-terminal (34–72) glycopeptides bearing a Man₉GlcNAc₂ (M9) oligosaccharide. Chemical shift perturbation mapping NMR experiments suggested that Phe65 of the glycopeptide specifically interacts with UGGT. To analyze this interaction, we constructed a glycopeptide library by varying Phe65 with 10 other natural amino acids, via parallel native chemical ligation between a glycopeptide-α-thioester and a peptide library consisting of 11 peptides. UGGT assay against the glycopeptide library revealed that, although less hydrophobic glycopeptides could be used as substrates for UGGT, hydrophobic glycopeptides are preferred

Early results of a phase-II study of modified short-course radiotherapy combined with capecitabine and delayed surgery for T3M0 lower rectal cancer

Early results of a phase-II study of modified short-course radiotherapy combined with capecitabine and delayed surgery for T3M0 lower rectal cance