title: Reversible cyclic peptide libraries for the discovery of affinity ligands.
abstract: A novel strategy is presented for the identification of cyclic peptide ligands from combinatorial libraries of reversible cyclic depsipeptides. A method for the solid-phase synthesis of individual cyclic depsipeptides and combinatorial libraries of these compounds is proposed, which employs lactic acid (Lact) and the dipeptide ester (Nα-Ac)-Ser(Ala)- as linkers for dilactonization. Upon alkaline treatment of the beads selected by screening a model library, the cyclic depsipeptides are linearized and released from the solid support to the liquid phase, to be sequenced via single-step tandem mass spectrometry (MS/MS). The protocol presented for library synthesis provides for wide structural diversity. Two model sequences, VVWVVK and AAWAAR, were chosen to present different structural examples for depsipeptide libraries and demonstrate the process of sequence determination by mass spectrometry. Further, a case study using the IgG binding cyclic depsipeptide cyclo[(Nα-Ac)-S(A)-RWHYFK-Lact-E] is presented to demonstrate the process of library screening and sequence determination on the selected beads. Finally, a method is shown for synthesis of the irreversible cyclic peptide corresponding to the proposed depsipeptide structure, to make the ligand stable to the aqueous acid and alkaline conditions encountered in affinity chromatographic applications. The cyclic peptide ligand was synthesized on a poly(methacrylate) resin and used for chromatographic binding of the target IgG.
authors.affiliation: Department of Chemical and Biomolecular Engineering, ‡Department of Molecular and Structural Biochemistry, and §Biomanufacturing Training and Education Center, North Carolina State University , Raleigh, North Carolina 27695, United States.
authors.forename: Stefano
authors.initials: S
authors.lastname: Menegatti
authors.forename: Kevin Lawrence
authors.initials: KL
authors.lastname: Ward
authors.forename: Amith Dattatray
authors.initials: AD
authors.lastname: Naik
authors.forename: William Stanley
authors.initials: WS
authors.lastname: Kish
authors.forename: Robert Kevin
authors.initials: RK
authors.lastname: Blackburn
authors.forename: Ruben Guillermo
authors.initials: RG
authors.lastname: Carbonell
mesh_terms: D008024:Ligands; D015394:Molecular Structure; D019151:Peptide Library; D010456:Peptides, Cyclic / Q000032:analysis*; D053719:Tandem Mass Spectrometry
chemical_list: D008024:Ligands; D019151:Peptide Library; D010456:Peptides, Cyclic