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Dernière mise à jour : Mai 2018

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Neuroendocrinologie Moleculaire de la Reproduction

An unprecedented access path to stable peptides in biological media

kisspeptin
© Julien Diharce

This is a significant advance in the chemistry of sugars. The chemists of the Biomolecule-Conception, Isolation and Synthesis laboratory (CNRS / Paris-Sud University) and the Center for Molecular Biophysics (CNRS) have developed a simple and original method for synthesizing thioglycosyl peptides. These conjugates of a peptide and a sugar whose oxygen is replaced by sulfur are very stable in a biological medium. This work, published in the journal Chemical Science, opens multiple applications in therapy and research.

Glycopeptides and glycoproteins are conjugates composed of a sugar linked to an amino acid chain (peptide) or a protein. They constitute the molecular architecture of many biomolecules and are widely present in all living organisms. This omnipresence makes them essential especially in medicine but the binding of sugar to the peptide / protein can be degraded by the enzymes present in the living. To follow a particular glycoconjugate or to deliver a glycoconjugate for medical use, it must therefore be made unassailable by these enzymes. What chemists from the Biomolecule-Conception, Isolation and Synthesis laboratory (CNRS / Université Paris-Sud) and the Center for Molecular Biophysics (CNRS) have just realized with a simpler method than before.
A conventional technique for making the conjugates stable is to replace the oxygen that binds the sugar moiety to the peptide / protein with a sulfur atom. The analog thus formed is called a thioglycoconjugate (thio- for sulfur) and is an excellent mimic of glycoconjugates, while remaining stable. Problem: the transformation to obtain it requires many synthesis steps, including complex steps of protection and deprotection of the different functions of the molecules to be conjugated.
In a single step, in neutral pH water and at room temperature, the team of Parisians and Orleans is much better than the classical method. Using amino acids having an aromatic iodinated ring as an anchor, in the presence of a palladium catalyst, they obtain thioglycoamino acids, "molecular bricks" of complex peptides. In the end, this method could be used to synthesize a long thioglycopeptide of 60 amino acids. This ease of access paves the way for a multitude of new, unprecedented molecules capable of mimicking the glycoproteins involved in various pathologies.

Reference

David Montoir, Mehdi Amoura, Zine El Abidine Ababsa, T. M. Vishwanatha, Expédite Yen-Pon,
Vincent Robert, Massimiliano Beltramo, Véronique Piller, Mouad Alami, Vincent Aucagne et Samir Messaoudi
Synthesis of Aryl-Thioglycopeptides Through Chemoselective Pd-Mediated Conjugation
Chemical ScienceSeptembre 2018