Asymmetric photoreactions as the origin of biomolecular homochirality: a critical review.
The role of asymmetric photoreactions (occurring in space or on the primitive Earth) in the origin of biomolecular homochirality is critically reviewed. A general description of the various possible ways for light to interact with chiral molecules is first presented on the basis of a series expansion of the dielectric constant: natural, magnetic and magnetochiral circular dichroism are identified with the first three terms in this development. Natural and magnetochiral circular dichroism may cause, through asymmetric photolysis, an enantiomeric excess in a racemic mixture of chiral molecules irradiated, respectively, by circularly polarized ultraviolet light, or by unpolarized ultraviolet light in the presence of a magnetic field non-perpendicular to the light beam. Terrestrial and extraterrestrial sites matching these conditions are then critically reviewed. Finally, we stress the possibility to arrive at the homochirality of amino acids through a path involving D-ribose during RNA world as an alternative to the usual scenarios operating directly on amino acids.
Institut d'Astronomie et d'Astrophysique, CP 226, and Département de Mathématique, CP 216, Université Libre de Bruxelles, Boulevard du Triomphe, B-1050 Bruxelles, Belgium. ajorisse@astro.ulb.ac.be
Alain
A
Jorissen
Corinne
C
Cerf
D000596:Amino Acids / Q000737:chemistry* / Q000528:radiation effects; D002942:Circular Dichroism; D008968:Molecular Conformation; D010777:Photochemistry; D013237:Stereoisomerism
D000596:Amino Acids