title: Enzymatic synthesis of a CCK-4 tripeptide fragment.
abstract: OBJECTIVE
  To synthesize a tripeptide derivative Phac-Met-Asp(OMe)-Phe -NH2, which is a fragment of the gastrin C-terminal tetrapeptide CCK-4, by enzymatic reaction.
  
  
  METHODS
  Three free enzymes, alpha-chymotrypsin, papain and thermolysin from acyl donor Phac-Met-OCam was involved in three steps. The choice of appropriate enzymes and solvents was selected.
  
  
  RESULTS
  All enzymatic reactions were obtained in reasonable yields(63%-92%). FAB-MS and FD-MS verified the correct molecular mass of the peptides.
  
  
  CONCLUSIONS
  Studies on the alpha-chymotrypsin catalyzed coupling reaction between Phac-Met-OCam and H-Asp(OMe)2 have focused on the low water content media. By papain catalyzed saponification of Phac-Met-Asp(OMe)2, alpha-methyl ester of aspartic acid is selectively hydrolyzed to retain beta-methyl ester, and Phac-Met-Asp(OMe)-OH and H-Phe-NH2 can be coupled efficiently by thermolysin.
authors.affiliation: West China School of Pharmacy, Sichuan University, Chengdu 610041, China.
authors.forename: Li
authors.initials: L
authors.lastname: Guo
authors.forename: Zi-min
authors.initials: ZM
authors.lastname: Lu
authors.forename: Heiner
authors.initials: H
authors.lastname: Eckstein
mesh_terms: D002918:Chymotrypsin / Q000378:metabolism; D010206:Papain / Q000378:metabolism; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000737:chemistry; D013758:Tetragastrin / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism*; D013820:Thermolysin / Q000378:metabolism
chemical_list: D010446:Peptide Fragments; D013758:Tetragastrin; D002918:Chymotrypsin; C117608:alpha-chymotrypsin; D010206:Papain; D013820:Thermolysin