Chemo-enzymatic synthesis of a bioactive peptide containing a glutamine-linked oligosaccharide and its characterization

Abstract

A bioactive peptide containing a glutamine-linked oligosaccharide was chemo-enzymatically synthesized by use of the solid-phase method of peptide synthesis and the transglycosylation activity of endo-β- N-acetylglucosaminidase. Substance P, a neuropeptide, is an undecapeptide containing two l-glutamine residues. A substance P derivative with an N-acetyl- d-glucosamine residue attached to the fifth or sixth l-glutamine residue from the N-terminal region was chemically synthesized. A sialo complex-type oligosaccharide derived from a glycopeptide of hen egg yolk was added to the N-acetyl- d-glucosamine moiety of the substance P derivative using the transglycosylation activity of endo-β- N-acetylglucosaminidase from Mucor hiemalis, and a substance P derivative with a sialo complex-type oligosaccharide attached to the l-glutamine residue was synthesized. This glycosylated substance P was biologically active, although the activity was rather low, and stable against peptidase digestion. The oligosaccharide moiety attached to the l-glutamine residue of the peptide was not liberated by peptide- N 4-( N-acetyl-β- d-glucosaminyl) asparagine amidase F.