Method for producing peptide

A method for producing a peptide comprising an amino acid residue having an —OH group, comprising converting an —SH group of a peptide comprising an amino acid residue having the —SH group to the —OH group, wherein said method comprises the following steps (a) to (c):

• (a) allowing the —SH group in a peptide to react with a methylating agent to convert the —SH group to an —SMe group;
• (b) allowing the —SMe group obtained in the step (a) to react with a cyanizing agent;
• and
• (c) modifying the reaction conditions to become more basic than the conditions in the step (b);
• wherein the peptide comprising an amino acid residue having the —SH group is a glycopeptide having an O-linked sugar chain, and a glycopeptide comprising an amino acid residue having the —OH group is obtained.

A method for producing a peptide comprising an amino acid residue having an —OH group, comprising converting an —SH group of a peptide comprising an amino acid residue having the —SH group to the —OH group, wherein said method comprises the following steps (a) to (c):

• (a) allowing the —SH group in a peptide to react with a methylating agent to convert the —SH group to an —SMe group;
• (b) allowing the —SMe group obtained in the step (a) to react with a cyanizing agent;
• and
• (c) modifying the reaction conditions to become more basic than the conditions in the step (b);
• wherein the peptide comprising an amino acid residue having the —SH group is a glycopeptide, and a glycopeptide comprising an amino acid residue having the —OH group is obtained;
• and
• wherein the amino acid residue having the —SH group is a threonine derivative A represented by the following Formula (1), and the production method further comprises the following step (o) before the step (a), and the —SH group of the threonine derivative A residue in the glycopeptide obtained in the step (o) reacts with the methylating agent in the step (a):
• (o) ligating a first glycopeptide whose C-terminus is represented by the following formula:
• -sugar Asn-X—C(═O)—SR
• (wherein sugar Asn represents a sugar chain-added asparagine,
• X represents a portion other than a carboxyl group of any given amino acid residue other than proline, and
• R is selected from a benzyl group, an aryl group, and an alkyl group, which may be substituted with substituents), to a second peptide containing a threonine derivative A residue at the N-terminus thereof according to a ligation method to obtain a glycopeptide containing a threonine derivative A represented by the following Formula (1):
• as an amino acid residue.

A glycopeptide having a structure represented by the following formula:

• -sugar Asn-X—Y—
• wherein sugar Asn represents a sugar chain-added asparagine,
• X represents any given amino acid residue other than proline, and
• Y represents a threonine derivative A residue represented by Formula (2):