ABSTRACT

The origin and evolution of biological homochirality are described from the viewpoint of astrobiology and asymmetric autocatalysis. Homochirality is one of the most important features of life. The important question of biological homochirality is how and when this symmetry-breaking occurred. Possible explanations of the origin of chirality on Earth are some chiral organic compounds from space, meteorites, irradiation by circularly polarized light, etc. However, the processes of propagation and amplification of chirality are required to reach homochirality. The asymmetric autocatalytic reaction has been proposed as a chemical reaction model for the amplification of enantiomeric excess. Pyrimidyl alkanol acts as an asymmetric autocatalyst, with significant amplification of enantiomeric excess in the addition reaction of diisopropylzinc to pyrimidine-5-carbaldehyde, i.e., the Soai reaction. The various chiral initiators related to astrobiology, such as amino acids in meteorites, the chirality of inorganic materials, and circularly polarized light, induce highly enantiomerically enriched organic compounds, in conjunction with asymmetric autocatalysis.