Kinetic analysis of artificial peptide self-replication. Part II: the heterochiral case.
A kinetic model has been designed to describe and to analyze the stereoselective behavior of a recently discovered heterochiral template-directed peptide self-replicator by Ghadiri and co-workers [Nature 409 (2001) 797-801]. It turned out that previous assumptions stating that exclusively homochiral species participate in a stereoselective and autocatalytic pathway and that heterochiral species originate only from uncatalyzed background reactions could not be validated by our model. On the contrary, excellent fitting of experimental data indicated that the whole combinatorial variety of possible cross-catalytic processes involving L- and D- peptide species play an important role and need to be taken into account. The system shows no net creation of chiral matter but only a redistribution of the initially present chiral material. Both, the separation of an optically inactive meso-type template dimer and a slight chiroselective autocatalytic effect, contribute to a predicted amplification of enantiomeric excess that, in some cases, can simultaneously result in a substantial amount of optically active matter.
Centro de Investigaciones Químicas, Universidad Autónoma del Estado de Morelos, Av. Universidad No 1001, Col. Chamilpa, 62210 Cuernavaca, Morelos, Mexico.
Jesús Rivera
JR
Islas
Véronique
V
Pimienta
Jean-Claude
JC
Micheau
Thomas
T
Buhse
D000465:Algorithms; D002384:Catalysis; D003198:Computer Simulation; D019418:Evolution, Chemical; D007700:Kinetics; D008956:Models, Chemical; D009716:Numerical Analysis, Computer-Assisted; D000069497:Origin of Life; D010455:Peptides / Q000737:chemistry* / Q000235:genetics; D013237:Stereoisomerism
D010455:Peptides