title: Protease-catalyzed peptide synthesis using inverse substrates: the synthesis of Pro-Xaa-bonds by trypsin.
abstract: Benzyloxycarbonyl-L-proline p-guanidinophenyl ester is an "inverse substrate" for trypsin; i.e., the cationic center is included in the leaving group instead of being in the acyl moiety. This substrate can be used in trypsin-catalyzed acyl-transfer reactions leading to the synthesis of Pro-Xaa peptide bonds. The reaction proceeds about 20 times slower than reaction with similar alanine-containing substrates, but the ratio between synthesis and hydrolysis is more favorable. The investigation of a series of nucleophiles led to information about the specificity of the process. Nucleophiles differing only in the P(1)'-position show an increasing acyl transfer efficiency in the order Phe < Gly < Ley < Ser < Ala < lle. C terminal elongation of the nucleophiles is of minor influence on their efficiency. The formation of an H bond between the acyl-enzyme and the nucleophile seems to play an important role in the aminolysis of the acyl-enzyme.
authors.affiliation: Karl Marx University, Biosciences Division, Department of Biochemistry, DDR-7010 Leipzig, Germany.
authors.forename: V
authors.initials: V
authors.lastname: Schellenberger
authors.forename: U
authors.initials: U
authors.lastname: Schellenberger
authors.forename: H D
authors.initials: HD
authors.lastname: Jakubke
authors.forename: N P
authors.initials: NP
authors.lastname: Zapevalova
authors.forename: Y V
authors.initials: YV
authors.lastname: Mitin