Automated Solid-Phase Synthesis of Cyclic Peptides Bearing a Side-Chain Tail Designed for Subsequent Chemical Grafting

A new strategy for synthesis of branched cyclic peptide by Asn side-chain hydrazide ligation

“…The HRMS detection of peak 2(Fig. 2a)displayed the m/z of 801.3145 that is highly in accordance with the calculated mass 801.3168 of the acylazide peptide QYN(N 3 )YST(8). The reaction of 8 and MPAA is extremely expeditious.…”

“…NMethyltrityl is an acid-labile protecting group for Lys side-chain amino group and selective deprotection exposed the amine for introducing a new peptide on the branch [6]. Allyl group was used in protection of Glu and Asp side-chain acid and was selectively deprotected with palladium reagents [7,8]. Using allyl-protected Glu and Dde-protected Lys, a branched cyclic peptide was successfully synthesized [9].…”

Selective RGD-Mediated Adhesion of Osteoblasts at Surfaces of Implants

“…This is additional proof for integrin-RGD-peptide interaction to be the cause for the observed cell adhesion. A comparison the ligand c(-RGDfK-) containing linkers A or B with the peptide c(-RGDEv-) synthesized by Delforge et al [7] (thiol peptide C) clearly indicate an improvement in cell adhesion with c(-RGDfK-) as ligand ( Figure 3). To coat the PMMA surface with c(-RGDfK-) the peptide was linked through a spacer to acrylic acid and then radically polymerized onto the PMMA graft.…”

Solid-phase synthesis and fluorine-18 radiolabeling of cycloRGDyK

“…Most synthetic methods towards cyclic peptides suffered from cyclodimerization, oligomerization, or racemization of the C-terminal residue. [16–20] Furthermore, aspartimide formation, N -acetylation, piperidine amide formation, and tetramethylguanidinium formation were also observed as byproducts during cyclic peptide synthesis. [16–20] …”

“…However, the automated procedure required a total of 8 equivalents of activating agent and cyclization times between 2–6 hours. [20] …”