We report the induction of chiroptical properties in 2 nm diameter gold nanoparticles passivated with short peptides characterized by the Aib-l-Ala repetition in their sequence. The nanoparticles present relevant ECD signals in the 300-650 nm wavelength region, corresponding to the gold nanoparticle's quantized electronic structure. Although the only chiral amino acid present in the peptide sequences is l-Ala, the particles show mirror image spectra like those of enantiomers according to the number of amino acids in the main chain (odd or even). Such a behavior appears to be strongly influenced by the secondary structure assumed by the peptides when passivating the nanoparticles and vanishes when the sequence is long enough to assume a 310-helix conformation. Moreover, chirality control is a reversible process and can be deactivated or reactivated by increasing or decreasing the temperature.

Liraglutide is a new generation lipopeptide drug used for the treatment of type II diabetes. In this work, we describe new approaches for its preparation fully by chemical methods. The key step of these strategies is the synthesis in solution of the Lys/γ-Glu building block, Fmoc-Lys-(Pal-γ-Glu-OtBu)-OH, in which Lys and Glu residues are linked through their side chains and γ-Glu is N(α) -palmitoylated. This dipeptide derivative is then inserted into the peptide sequence on solid phase. As liraglutide is obtained with great purity and high yield, our approach can be particularly attractive for an industrial production. We also report here the results of a circular dichroism conformational analysis in a membrane mimetic environment that offers new insights into the mechanism of action of liraglutide. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.

The hydrolysis and rearrangement of the dihydroorotic (Hor) residue in the presence of bases, leading to the formation of the hydantoin (Hyd) impurity, represent one of the major problems in manufacturing of the gonadotropin-releasing hormone antagonist Degarelix. In an attempt to find efficient strategies to overcome this problem, we carried out a screening of organic bases in order to select those which afforded both the rapid Fmoc deprotection during the solid-phase synthesis and the absence of this peculiar rearrangement. Among the bases tested, only tert-butylamine did not affect the peptide molecule and was able to perform fast Fmoc removal. The use of tert-butylamine for the synthesis of Degarelix led to a product with excellent purity and yield without a detectable amount of the hydantoin impurity. Thus, we showed that tert-butylamine can be a suitable alternative to piperidine for industrial-scale production of Degarelix or other Hor-containing peptide pharmaceuticals.

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Three approaches for the chemical ligation of peptides to cotton fibers are described and compared. This investigation was encouraged by the need to create peptide-decorated natural textiles, furnished with useful properties (e.g. antimicrobial activity). IR absorption spectroscopy is proved to be an easy and fast method to check the covalent anchorage of a peptide to cotton, whereas for a quantitative determination, a UV absorption method was employed. We also analyzed the usefulness of electron paramagnetic resonance spectroscopy to characterize our peptide-cotton conjugates.