title: Cobalt(III)-ligated peptides as acyl acceptors in peptide synthesis catalyzed by chymotrypsin.
abstract: The efficiency of cobalt(III)-ligated peptides as acceptor nucleophiles in acyl transfer reactions catalyzed by alpha-chymotrypsin was examined. A series of metallopeptides with the general formula [H-(Gly)n-OCo(NH3)5]2+ (1 < or = n < or = 4) was tested. The aminolysis rate of acyl-chymotrypsin was measured spectrophotometrically by monitoring the concentration of unreacted nucleophile. The rate of the competing hydrolysis of acyl-chymotrypsin was obtained by automatic titration with base, using a pH-stat. The main result was that the positively charged metallopeptides, in general, were more efficient nucleophiles than the corresponding amides and free peptides that were examined for comparison. A binding model that rationalizes the findings is given.
authors.affiliation: Chemistry Department A, Technical University of Denmark, Lyngby.
authors.forename: M F
authors.initials: MF
authors.lastname: Andreasen
authors.forename: S
authors.initials: S
authors.lastname: Bagger
authors.forename: A M
authors.initials: AM
authors.lastname: Sørensen
authors.forename: K
authors.initials: K
authors.lastname: Wagner
mesh_terms: D000595:Amino Acid Sequence; D002384:Catalysis; D002918:Chymotrypsin / Q000737:chemistry*; D003035:Cobalt / Q000737:chemistry*; D007700:Kinetics; D008969:Molecular Sequence Data; D010453:Peptide Synthases / Q000737:chemistry; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry*; D013053:Spectrophotometry; D013816:Thermodynamics
chemical_list: D010455:Peptides; D003035:Cobalt; D002918:Chymotrypsin; D010453:Peptide Synthases