On the prebiotic synthesis of D-sugars catalyzed by L-peptides: assessments from first-principles calculations.
What accounts for a particular chiral selection in the case of a few sugars of prebiotic relevance, thereby mirroring the asymmetry observed in nature? By using first-principles calculations, the generation of pentoses from glycolaldehyde (the initial product of the autocatalytic formose reaction), which has been detected in outer space), has been modeled by using L-Val-L-Val as a primeval catalyst. Our theoretical study provides insight into the mechanism of this reaction and satisfactorily explains a few key molecular events. Our rationale agrees with the reported experimental data and shows that the D-configuration is only favored for ribose. L-pentoses are usually favored in the presence of L-configured dipeptides, as observed experimentally, although no chiral selection could be observed in the case of xylose. These results confirm that a prebiotic sugar soup could be fine-tuned in the presence of shorter peptides as catalysts and that D-ribose would have also resulted in an advantageous imbalance for further amplification and chemical evolution.
Department of Organic and Inorganic Chemistry, University of Extremadura, Avda. de Elvas s/n, 06006 Badajoz, Spain. dcannie@unex.es
David
D
Cantillo
Martín
M
Ávalos
Reyes
R
Babiano
Pedro
P
Cintas
José L
JL
Jiménez
Juan C
JC
Palacios
D002241:Carbohydrates / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D004151:Dipeptides / Q000737:chemistry*; D015394:Molecular Structure; D056692:Prebiotics; D013237:Stereoisomerism
D002241:Carbohydrates; D004151:Dipeptides; D056692:Prebiotics