Homochiral oligopeptides via a lattice-controlled polymerisation in racemic crystals of valine N-carboxyanhydride suspended in aqueous solutions. - Université Pierre et Marie Curie Accéder directement au contenu
Article Dans Une Revue Chemistry - A European Journal Année : 2007

Homochiral oligopeptides via a lattice-controlled polymerisation in racemic crystals of valine N-carboxyanhydride suspended in aqueous solutions.

Résumé

As part of our program on the biochirogenesis of homochiral peptides, we report the formation of racemic parallel (p) beta sheets composed of alternating R and S chains of up to 14-15 repeat units of the same handedness through the polymerisation of (R,S)-valine N-carboxyanhydride (NCA) crystals suspended in aqueous solutions of a primary amine as the initiator. The occurrence of such a lattice-controlled reaction accompanied by a reduction in volume implies the operation of a mechanism that differs from that of the common solid-state polymerisation in vinyl systems. The topotacticity of the reaction is explained through the operation of a multistep nonlinear process comprising lattice control coupled with an asymmetric induction in the formation of homochiral short peptides followed by their self-assembly into racemic p beta sheets, which operate as efficient templates in the ensuing process of enantioselective chain elongation at the polymer/crystal interface. The composition of the diastereoisomeric libraries of oligopeptides was determined by MALDI-TOF and MALDI-TOF-TOF MS analyses of the products obtained from monomers enantioselectively labelled with deuterium. The structure of the p beta sheets could be determined by initiating the polymerisation reaction with water-soluble esters of enantiopure alpha-amino acids or short peptides. The same reaction performed with the monomer crystals suspended in hexane yielded a complex mixture of diastereoisomeric oligopeptides, thus highlighting the indispensable role played by water in controlling the stereoselectivity of the reaction. By contrast, polymerisation of (R,S)-leucine NCA crystals, with a different packing arrangement that presumably does not endorse the formation of periodic peptide templates, yielded, both in aqueous and hexane suspensions, libraries of peptides dominated by heterochiral diastereoisomers.

Domaines

Chimie organique

Dates et versions

hal-00689870 , version 1 (20-04-2012)

Identifiants

Citer

Ran Eliash, Jose G Nery, Irena Rubinstein, Gilles Clodic, Gérard Bolbach, et al.. Homochiral oligopeptides via a lattice-controlled polymerisation in racemic crystals of valine N-carboxyanhydride suspended in aqueous solutions.. Chemistry - A European Journal, 2007, 13 ((36)), pp.10140-51. ⟨10.1002/chem.200700994⟩. ⟨hal-00689870⟩
56 Consultations
0 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More