title: Enzymatic peptide synthesis in frozen aqueous solution: use of N alpha-unprotected peptide esters as acyl donors.
abstract: The ability of the endopeptidase alpha-chymotrypsin (EC 3.4.21.1) to catalyse the reaction of various N alpha-unprotected di- and tripeptide ester derivatives with H-Leu-NH2, and with a series of C-terminal free di- and tripeptides at -15 degrees C in frozen aqueous solution was investigated. The enzyme is able to synthesize N- and C-terminal unprotected penta- and hexapeptides in up to 92% yield, depending on the amino component used, in a single-step segment-condensation reaction. Freezing the reaction mixture resulted in significantly increased peptide yields compared with the reaction at room temperature. The enzyme shows a modified nucleophilic specificity in frozen solution compared with room temperature. Nucleophilic amino components with positively charged amino acids in P2'-position are accepted.
authors.affiliation: Faculty of Biosciences, Pharmacy and Psychology, Leipzig, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Gerisch
authors.forename: H D
authors.initials: HD
authors.lastname: Jakubke
mesh_terms: D002384:Catalysis; D002918:Chymotrypsin / Q000737:chemistry*; D004151:Dipeptides / Q000737:chemistry; D004952:Esters; D005615:Freezing; D009842:Oligopeptides / Q000138:chemical synthesis* / Q000737:chemistry; D012996:Solutions; D013379:Substrate Specificity; D013696:Temperature; D014867:Water
chemical_list: D004151:Dipeptides; D004952:Esters; D009842:Oligopeptides; D012996:Solutions; D014867:Water; D002918:Chymotrypsin