Chiral amplification of oligopeptides via polymerization in two-dimensional crystallites on water.
A possible role that might have been played by ordered clusters at the air/water interface for the generation of homochiral oligopeptides under prebiotic conditions has been probed by a catalyzed polymerization of amphiphilic activated alpha-amino acids that assembled as two-dimensional (2-D) crystallites at this interface. Three type of processes are described: (i) polymerization of racemates of activated alpha-amino acids that undergo spontaneous resolution into enantiomorphous 2-D crystallites to yield racemic mixtures of oligopeptides enriched with the oligomers of homochiral sequence, (ii) enhanced formation of racemic mixtures of homochiral oligopeptides via lattice-controlled polymerization within 2-D racemic compounds and (iii) generation of homochiral oligopeptides of a single handedness from chiral non-racemic mixtures of monomers that self-assemble into two different phases, racemic crystallites composed from both enantiomers and enantiomorphous crystallites of the enantiomer in excess. The structures of the 2-D crystallites have been determined by grazing incidence X-ray diffraction and the diastereoisomeric composition of the oligopeptides by matrix-assisted laser-desorption time-of-flight mass spectrometry with enantio-labeling.
Weissbuch
Isabelle
I
Department of Materials and Interfaces, The Weizmann Institute of Science, 76100-Rehovot, Israel.
Bolbach
Gerard
G
Leiserowitz
Leslie
L
Lahav
Meir
M
D001704:Biopolymers / Q000737:chemistry*; D008958:Models, Molecular; D009842:Oligopeptides / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013237:Stereoisomerism; D014867:Water / Q000737:chemistry*
D001704:Biopolymers; D009842:Oligopeptides; D014867:Water