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Self-assembled Peptide Nanostructures and Their Applications
Published in Klaus D. Sattler, st Century Nanoscience – A Handbook, 2020
The use of aromatic moieties at the N-terminal site is another approach to induce the self-assembly by π–π stacking interactions. One of the common capped aromatic moieties is Fmoc (9-fluorenylmethoxycarbonyl) group. Various peptide combinations have been capped with Fmoc group. Cheng et al. designed two Fmoc-capped tripeptides, one of which formed highly anisotropic fibrils (FmocVLK-Boc) and the other (Fmoc-K(Boc)LV) formed highly branched fibrils. Both the peptides formed hydrogels in borate buffer solution. The interchange of the position of K and V in tripeptide sequences leads to the formation of different self-assembled structures, indicating an important approach to control hydrogel behavior (Cheng et al. 2010). Fmoc-FG, Fmoc-FRGD, Fmoc-RGDF, and Fmoc-FF peptides also showed self-assembled nanofibrous structures in their hydrogel state (Figure 2.15) (Orbach et al. 2009).
Solid-phase synthesis of sulfur containing heterocycles
Published in Journal of Sulfur Chemistry, 2018
p-Alkoxybenzyl alcohol linker was attached on an MBHA resin and on a Wang resin. Fmoc-protected phenylalanine was coupled to the resin in the presence of DMAP and DIC in dimethylformamide and dichloromethane. The 20% piperidine in dimethylformamide was utilized for the removal of Fmoc group. The resin-bound phenylalanine was reductively alkylated with 4-methoxybenzaldehyde in step 2. The chlorosulfonyl isocyanate and formic acid were reacted to form sulfamoyl chloride. The sulfamoyl chloride was immediately reacted to produce the resin-bound sulfamide intermediate in the presence of 2,4,6-collidine (Scheme 32). Finally the target products were afforded by cleavage with DBU in dichloromethane [19,64].
Evaluation of greener solvents for solid-phase peptide synthesis
Published in Green Chemistry Letters and Reviews, 2021
Katarzyna Wegner, Danielle Barnes, Kim Manzor, Agnieszka Jardine, Declan Moran
Project C involved the manufacture of cyclic octapeptide, composed of five unnatural amino acids, three natural amino acids and a small molecule residue (Figure 7). The amino acids used for the manufacture of peptide C were Fmoc protected. For project C, nine solvents were preliminarily examined as replacements for DMF in SPPS.
Rhodiasolv PolarClean – a greener alternative in solid-phase peptide synthesis
Published in Green Chemistry Letters and Reviews, 2021
Ashish Kumar, Anamika Sharma, Beatriz G. de la Torre, Fernando Albericio
We next tested the efficiency of PolarClean (also compared with DMF) for SPPS. To this end, we targeted three model peptides: (A) H-Tyr-Gly–Gly-Phe-Leu-NH2 (Leu enkephalinamide), (B) H-Ala-Lys-Asp-Gly-Tyr-Ile-NH2 (fragment 1–6 of the toxin II from scorpion Androctonus australis Hector (27) and C) H-Lys-Thr-Thr-Lys-Ser-NH2 (peptide-4 used as an anti-wrinkle agent in cosmetics) (28). These model peptides were synthesized on Fmoc-RinkAmide AM-PS (0.1 mmol scale, loading 0.64 mmol/g) using PolarClean for all synthetic steps, namely Fmoc removal, coupling, and washings. Coupling and Fmoc removal steps were performed at 45°C (because of the high viscosity of the solvent). Coupling was performed using a three-fold excess of equimolar Fmoc-AA-OH-N,N’-diisopropylcarbodiimide (DIC)-OxymaPure (1:1:1) with respect to resin, with 1 min pre-activation followed by coupling for 1 h. Fmoc removal was accomplished with a 20% piperidine solution in the respective solvent for 10 min. After global deprotection with trifluoroacetic acid (TFA)-triisopropylsilane-H2O (9.5:2.5:2.5), the peptide was precipitated in ether and lyophilized. Analysis by high-performance liquid chromatography (HPLC) (Figure 3) showed that the target peptide was obtained as a major peak in all cases, with a clean chromatographic profile for further purification if required. In this regard, the performance of the synthesis using PolarClean was very similar to that using DMF. In the case of peptide B containing the sequence Asp-Gly which is used to study aspartimide formation (27), it is important to highlight that the absence of the β-peptide during analysis, which is the proof of the mentioned side-reaction. For peptides B and C (Figure 3), some small hydrophobic peaks were observed, which could correspond to the reaction of the methyl ester of PolarClean with the free amino group on the growing peptide chain during Fmoc removal, as also reported for other ester-based solvents such as PC (14, 29) and, to a lesser extent, GVL (10, 11). See Supplementary Information for HPLC comparison between PolarClean and DMF synthesis and mass spectra of the final peptides.