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The complex-type N-linked octasaccharide oxazoline having LacNAc as the nonreducing end sugar was efficiently synthesized using the benzyl-protected LacNAc, mannose, and β-mannosyl GlcNAc units as key building blocks. To achieve a highly β-selective glycosylation with the LacNAc unit, the N-trichloroacetyl group was used for the protection of the amino(More)
The biantennary complex-type N-glycans bearing LacNAc and LacdiNAc as the nonreducing end motif were synthesized in a protected form suitable to use in the Fmoc solid-phase peptide synthesis studies. Two approaches for the nonasaccharide synthesis were examined by taking advantage of the highly β-selective glycosylation with GlcNTCA(More)
The chemical synthesis of human interleukin-2 (IL-2) , having a core 1 sugar, by a ligation method is reported. Although IL-2 is a globular glycoprotein, its C-terminal region, in particular (99-133), is extremely insoluble when synthesized by solid-phase method. To overcome this problem, the side-chain carboxylic acid of the Glu residues was protected by a(More)
We developed a one-pot peptide ligation method using two orthogonal thioester precursors and a protecting group for the ligation reaction between Asp and Cys. Combination of the two precursors facilitated the one-pot operation and yielded the entire polypeptide. The usefulness of this method was successfully demonstrated by the total synthesis of histone H4.
A new solid-phase disulfide ligation method is developed to prepare a disulfide peptide from two types of Cys-containing peptide fragments with minimum purification steps. In combination with the subsequent intramolecular amide bond formation, a cyclic nonapeptide, oxytocin, was efficiently synthesized as a fundamental model for more complex cyclic peptides.
A novel GlcNAc-Asn unit carrying trifluoroacetic acid (TFA)-sensitive O-protecting groups was prepared. The unit was used for the solid-phase peptide synthesis (SPPS) of the N-acetylglucosaminylated emmprin (35-69) thioester via one-step deprotection by TFA combined with the N-alkylcysteine thioesterification method. This segment was used for the synthesis(More)
Synthetic insulin analogues with a long lifetime are current drug targets for the therapy of diabetic patients. The replacement of the interchain disulfide with a diselenide bridge, which is more resistant to reduction and internal bond rotation, can enhance the lifetime of insulin in the presence of the insulin-degrading enzyme (IDE) without impairing the(More)