Oligopeptides and Copeptides of Homochiral Sequence, via beta-Sheets, from Mixtures of Racemic alfa-Amino Acids, in a One-Pot Reaction in Water; Relevance to Biochirogenesis

FABRICIO R. BISOGNO

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY

AMER CHEMICAL SOC

Lugar: Washington; Año: 2008 vol. 130 p. 8651 - 8651

0002-7863

s part of our studies on the biochirogenesis of peptides of homochiral sequence during earlyevolution, the formation of oligopeptides composed of 14-24 residues of the same handedness in thepolymerization of DL-leucine (Leu), DL-phenylalanine (Phe), and DL-valine (Val) in aqueous solutions, byactivation with N,N′-carbonyldiimidazole and then initiation with a primary amine, in a one-pot reaction,was demonstrated by MALDI-TOF MS using deuterium enantio-labeled R-amino acids. The formation oflong isotactic peptides is rationalized by the following steps occurring in tandem: (i) creation of a library ofshort diasteroisomeric oligopeptides containing isotactic peptides in excess in comparison to a binomialkinetics, as a result of an asymmetric induction exerted by the N-terminal residue of a given handedness;(ii) precipitation of the less soluble racemic isotactic penta- and hexapeptides in the form of -sheets thatare delineated by homochiral rims; (iii) regio-enantiospecific chain