title: Plural origins of molecular homochirality in our biota Part II. The relative stabilities of homochiral and mixed oligoribotides and peptides.
abstract: By computer simulations--molecular mechanics and molecular dynamics with the amber force field (Weiner et al, (1986), J. Comp. Chem. 7, 230-252)--we have determined the stabilities of oligoribotide strands built with D- and L-riboses, and of peptide chains with D- and L-amino acid residues. In particular, complementary double-chains of oligoribotides were studied, since they are an important feature of the growing mechanism of modern nucleic acids. Peptide chains on the other hand, grow without need of a template. We found that mixed oligoribotides are less stable than homochiral ones, and that this chiral effect is less noticeable in peptide chains. The results support the interpretation that L-riboses act as terminators to the template-assisted growth of oligo-r-GD (enantiometric cross-inhibition; Joyce et al., (1987), Proc. Natl. Acad. Sci. USA 84, 4398-4402). Based on this effect, a chemical pathway is proposed which could, under assumed prebiotic conditions, bypass the hindrance of homochiral growth.
authors.affiliation: Departamento de Química Fundamental, Universidade Federal de Pernambuco, Brasil.
authors.forename: T A
authors.initials: TA
authors.lastname: Soares
authors.forename: R D
authors.initials: RD
authors.lastname: Lins
authors.forename: R
authors.initials: R
authors.lastname: Longo
authors.forename: R
authors.initials: R
authors.lastname: Garratt
authors.forename: R
authors.initials: R
authors.lastname: Ferreira
mesh_terms: D004247:DNA / Q000737:chemistry*; D004355:Drug Stability; D007536:Isomerism; D008957:Models, Genetic; D009690:Nucleic Acid Conformation; D009843:Oligoribonucleotides / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry*; D012266:Ribose / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D009843:Oligoribonucleotides; D010455:Peptides; D011506:Proteins; D012266:Ribose; D004247:DNA