title: Protease-catalyzed peptide synthesis for the site-specific incorporation of alpha-fluoroalkyl amino acids into peptides.
abstract: Substitution of native amino acids by fluoroalkyl analogues represents a new approach for the design of biologically active peptides with increased metabolic stability as well as defined secondary structure and provides a powerful label for spectroscopic investigations. Here, we introduce a methodology for the incorporation of sterically demanding C(alpha)-fluoroalkyl amino acids into the P(1) position of peptides catalyzed by the commercially available proteases trypsin and alpha-chymotrypsin. The combination of 4-guanidinophenyl ester of C(alpha)-fluoroalkyl amino acids as substrate mimetics with frozen-state reaction conditions provided the most efficient strategy for protease-catalyzed site-specific introduction of this kind of nonnatural amino acids into peptide sequences. Consequently, a library of di-, tri-, and tetrapeptides containing alpha-methyl, alpha-difluoromethyl, and alpha-trifluoromethyl alanine, leucine, and phenylalanine in the P(1) position was synthesized catalyzed by trypsin as well as alpha-chymotrypsin. Trypsin was shown to be the more versatile protease.
authors.affiliation: Department of Organic Chemistry, University of Leipzig, Germany.
authors.forename: Sven
authors.initials: S
authors.lastname: Thust
authors.forename: Beate
authors.initials: B
authors.lastname: Koksch
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D002384:Catalysis; D002918:Chymotrypsin / Q000378:metabolism*; D005463:Fluoroacetates; D006146:Guanidines / Q000138:chemical synthesis*; D008958:Models, Molecular; D018716:Molecular Mimicry; D015394:Molecular Structure; D010452:Peptide Biosynthesis; D010455:Peptides / Q000032:analysis / Q000138:chemical synthesis / Q000737:chemistry; D010649:Phenylalanine / Q000031:analogs & derivatives* / Q000138:chemical synthesis*; D015202:Protein Engineering; D014269:Trifluoroacetic Acid / Q000138:chemical synthesis; D014357:Trypsin / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D005463:Fluoroacetates; D006146:Guanidines; D010455:Peptides; C067538:N-benzyloxycarbonylphenylalanine methyl ester; D010649:Phenylalanine; D014269:Trifluoroacetic Acid; D002918:Chymotrypsin; D014357:Trypsin