Better Peptides via Chemical Glycosylation: Somatostatin Analogues Having a Human Complex-Type N-Glycan with Improved Drug Properties.

Somatostatin (somatotropin release-inhibiting factor, SRIF) is a growth hormone inhibitory factor in the form of a 14- or 28-amino acid peptide. SRIF affects several physiological functions through its action on five distinct SRIF receptor subtypes (sst1-5). Native SRIF has only limited clinical applications due to its rapid degradation in plasma.

Chemical synthesis of homogeneous human glycosyl-interferon-β that exhibits potent antitumor activity in vivo.

Chemical synthesis of homogeneous human glycoproteins exhibiting bioactivity in vivo has been a challenging task. In an effort to overcome this long-standing problem, we selected interferon-β and examined its synthesis. The 166 residue polypeptide chain of interferon-β was prepared by covalent condensation of two synthetic peptide segments and a glycosylated synthetic peptide bearing a complex-type glycan of biological origin.

2D selective-TOCSY-DQFCOSY and HSQC-TOCSY NMR experiments for assignment of a homogeneous asparagine-linked triantennary complex type undecasaccharide.

The assignment of (1)H and (13)C NMR signals of a complex type triantennary asialooligosaccharide was examined using 2D selective-TOCSY-DQFCOSY and HSQC-TOCSY experiments. The 2D selective-TOCSY-DQFCOSY experiment exhibits a 2D DQFCOSY spectrum of an individual monosaccharide in the undecasaccharide, although the NMR signals of several monosaccharides in the triantennary undecasaccharide are heavily overlapped. Selective excitation of each anomeric proton signal and subsequent TOCSY experiment afforded transverse magnetization corresponding to all of the proton signals of the monosaccharide.

Chemoenzymatic synthesis of diverse asparagine-linked alpha-(2,3)-sialyloligosaccharides.

Partial sialyl transfer reaction by alpha-(2,3)-sialyltransferase toward (Gal-beta-1,4-GlcNAc-beta-1,2-Man-alpha-1,6/1,3-)(2)Man-beta-1,4-GlcNAc-beta-1,4-GlcNAc-beta-1-asparagine-Fmoc 1 was examined to obtain mono-alpha-(2,3)-sialyloligosaccharides and then branch-specific exo-glycosidase digestion (beta-D-galactosidase, N -acetyl-beta-D-glucosaminidase and alpha-D-mannosidase) toward the asialo-branch was performed to obtain diverse asparagine-linked complex type alpha-(2,3)-sialyloligosaccharides. In addition, two kinds of disialyloligosaccharides in which the sialyl linkage was a mixture of alpha-(2,3)- and alpha-(2,6)-types were also specifically prepared by an additional alpha-(2,6)-sialyltransferase reaction toward mono-alpha-(2,3)-sialyloligosaccharides thus obtained.