| abstract |
PURPOSE: To enable industrial and advantageous obtaining of a peptide in good yield by treating a specific peptide with a proteolytic enzyme. n CONSTITUTION: About 1l solvent prepared by mixing a phosphoric acid buffer solution with a water-miscible organic solvent, such as ethanol, at (2-8):(8:2) volume ratio is added to about 1g peptide expressed by formula I (A is Ser, Gly or Ala; B is Asn or Ser; X is OH or normally used protecting group in peptide chemistry, amino acid residue or peptide residue; n is 3-7; the respective amino acid residues can be protected with normally used protecting group in the peptide chemistry) to provide a reaction medium. A proteolytic enzyme, such as thermolysin, is then added to the resultant reaction medium and cyclizing reaction is carried out at 20-50°C and pH4-10 to afford a reaction product, which is subsequently filtered, concentrated and purified to produce a peptide expressed by formula II. n COPYRIGHT: (C)1990,JPO&Japio |