Process for preparing glycopeptides having asparagine-linked oligosaccharides, and the glycopeptides
Glycopeptide having at least one asparagine-linked oligosaccharide at a desired position of the peptide chain which is obtained by: (1) esterifying hydroxyl of a resin and carboxyl of an amino acid having amino group nitrogen protected with a fat-soluble protective group (AGFPG), (2) removing the protective group to form a free amino group, (3) amidating the free amino group and carboxyl of an amino acid having AGFPG, (4) removing the protective group, (5) repeating the steps (3) and (4), (6) amidating the free amino group and carboxyl of the asparagine portion of an asparagine-linked oligosaccharide having AGFPG, (7) removing the protective group, (8) amidating the free amino group and carboxyl of an amino acid having AGFPG, (9) repeating steps (7) and (8), (10) removing the protective group, and (11) cutting off the resin with an acid; glycopeptide obtained by transferring sialic acid or a derivative thereof to the above glycopeptide.
1. A process for preparing a glycopeptide having at least one asparagine-linked oligosaccharide at a desired position of the peptide chain thereof, the process comprising:
(1) esterifying a hydroxyl group of a resin having the hydroxyl group and a carboxyl group of an amino acid having amino group nitrogen protected with a fat-soluble protective group,
(2) removing the fat-soluble protective group to form a free amino group,
(3) amidating the free amino group and a carboxyl group of an amino acid having amino group nitrogen protected with a fat-soluble protective group,
(4) removing the fat-soluble protective group to form a free amino group,
(5) repeating the steps (3) and (4) at least once,
(6) preparing an asparagine-linked disialooligosaccharide or an asparagine-linked monosialooligosaccharide having amino group nitrogen protected with a fat-soluble protective group and the carboxyl group of the sialic acid protected with a benzyl or allyl group, wherein the benzyl or allyl group is introduced into the carboxyl group of the sialic acid under a condition of pH 5 to 6,
(7) amidating the free amino group and a carboxyl group of the asparagine portion of the asparagine-linked disialooligosaccharide or the asparagine-linked monosialooligosaccharide having amino group nitrogen protected with a fat-soluble protective group and the carboxyl group of the sialic acid protected with a benzyl or allyl group,
(8) removing the fat-soluble protective group to form a free amino group,
(9) amidating the free amino group and a carboxyl group of an amino acid having amino group nitrogen protected with a fat-soluble protective group,
(10) repeating the steps (8) and (9) at least once,
(11) removing the fat-soluble protective group to form a free amino group, and cutting off the resin with an acid.
2. The process for preparing a glycopeptide according to claim 1 wherein the asparagine-linked disialooligosaccharide or asparagine-linked monosialooligosaccharide of step (6) has at least 6 sugar residues.
3. The process for preparing a glycopeptide according to claim 1 wherein the asparagine-linked disialooligosaccharide or asparagine-linked monosialooligosaccharide of step (6) has 9 to 11 sugar residues.
4. The process for preparing a glycopeptide according to claim 1 wherein the asparagine-linked disialooligosaccharide or asparagine-linked monosialooligosaccharide of step (6) has attached thereto a bifurcated oligosaccharide having at least 6 sugar residues.
5. The process according to claim 1 wherein the protective group for the carboxyl group of the sialic acid is benzyl group.
6. The process according to claim 2 wherein the protective group for the carboxyl group of the sialic acid is benzyl group.
7. The process according to claim 3 wherein the protective group for the carboxyl group of the sialic acid is benzyl group.
8. The process according to claim 4 wherein the protective group for the carboxyl group of the sialic acid is benzyl group.