10.1021/jo500699m.s001 Olivier Cheneval Olivier Cheneval Christina I. Schroeder Christina I. Schroeder Thomas Durek Thomas Durek Phillip Walsh Phillip Walsh Yen-Hua Huang Yen-Hua Huang Spiros Liras Spiros Liras David A. Price David A. Price David J. Craik David J. Craik Fmoc-Based Synthesis of Disulfide-Rich Cyclic Peptides American Chemical Society 2014 peptide engineering SPPS kalata B 1. drug discovery method synthesis cyclic 2014-06-20 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Fmoc_Based_Synthesis_of_Disulfide_Rich_Cyclic_Peptides/2280885 Disulfide-rich cyclic peptides have exciting potential as leads or frameworks in drug discovery; however, their use is faced with some synthetic challenges, mainly associated with construction of the circular backbone and formation of the correct disulfides. Here we describe a simple and efficient Fmoc solid-phase peptide synthesis (SPPS)-based method for synthesizing disulfide-rich cyclic peptides. This approach involves SPPS on 2-chlorotrityl resin, cyclization of the partially protected peptide in solution, cleavage of the side-chain protecting groups, and oxidization of cysteines to yield the desired product. We illustrate this method with the synthesis of peptides from three different classes of cyclic cystine knot motif-containing cyclotides: MoĢˆbius (M), trypsin inhibitor (T), and bracelet (B). We show that the method is broadly applicable to peptide engineering, illustrated by the synthesis of two mutants and three grafted analogues of kalata B1. The method reduces the use of highly caustic and toxic reagents and is better suited for high-throughput synthesis than previously reported methods for producing disulfide-rich cyclic peptides, thus offering great potential to facilitate pharmaceutical optimization of these scaffolds.