Microwave irradiation as a versatile tool for increasing reaction rates and yields in synthesis of optically active polyamides containing flexible l-leucine amino acid

High-molecular-weight poly(Gly-Val-Gly-Val-Pro) synthesis through microwave irradiation

In this study, we synthesized a polypeptide from its pentapeptide unit using microwave irradiation. Effective methods for polypeptide synthesis from unit peptides have not been reported. Here, we used a key elastin peptide, H-GlyValGlyValPro-OH (GVGVP), as the monomer peptide. It is difficult to obtain poly(Gly-Val-Gly-Val-Pro) (poly(GVGVP)) from the pentapeptide unit of elastin, GVGVP, via polycondensation. Poly(GVGVP) prepared from genetically recombinant Escherichia coli is a well-known temperature-sensitive polypeptide, and this temperature sensitivity is known as the lower critical solution temperature. When microwave irradiation was performed in the presence of various additives, the pentapeptide (GVGVP) polycondensation reaction proceeded smoothly, resulting in a product with a high molecular weight in a relatively good yield. The reaction conditions, like microwave irradiation, coupling agents, and solvents, were optimized to increase the reaction efficiency. The product exhibited a molecular weight greater than Mr 7000. Further, the product could be synthesized on a gram scale. The synthesized polypeptide exhibited a temperature sensitivity that was similar to that of poly(GVGVP) prepared from genetically recombinant E. coli. Therefore, this technique offers a facile and quick approach to prepare polypeptides in large amounts. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.

Synthesis, characterization and in vitro antimicrobial and biodegradability study of pseudo-poly(amino acid)s derived from N,N'-(pyromellitoyl)-bis-L-tyrosine dimethyl ester as a chiral bioactive diphenolic monomer

In this investigation N,N'-(pyromellitoyl)-bis-L-tyrosine dimethyl ester (7) as a chiral bioactive diphenolic monomer was prepared in three steps. The aim of this work was to obtain novel optically and biologically active pseudo-poly(amino acid)s (PAA)s that are more soluble in common organic solvents while maintaining their high thermal stability. Thus, several new, highly soluble, thermally stable, optically active and biodegradable PAAs containing different amino acid moieties in the main chain were prepared with moderate molecular weights via direct polycondensation using tosyl chloride, pyridine and N,N'-dimethylformamide as a condensing agent. The resulting novel polymers were characterized with FT-IR, (1)H-NMR, elemental and thermogravimetric analysis techniques. In addition, in vitro toxicity and biodegradability behavior of the diphenolic monomer 7, different synthetic diacids (3a-3e) and obtained PAAs, which were investigated in culture media, showed that the synthesized compounds and polymers derived from them are biologically active and biodegradable under a natural environment.