Parity violation and the evolution of biomolecular homochirality

Noise-induced symmetry breaking far from equilibrium and the emergence of biological homochirality

“…Unlike electromagnetic interactions, the weak interaction violates mirror symmetry [26,27]. Even though weak interactions have a negligible effect at molecular scales, it has been argued that it can cause an asymmetry affecting the rate of production of two enantiomers in a manner that over billions of years could lead to an observable level of enantiomeric imbalance [5,6].…”

“…There are those who argue that homochirality must have preceded the first chemical systems undergoing Darwinian evolution, and there are those who believe homochirality is a consequence of life, but not a prerequisite [3]. There are even those who argue that homochirality is a consequence of underlying asymmetries from the laws of physics, invoking complicated astrophysical scenarios for the origin of chiral organic molecules [4] or even the violation of parity from the weak interactions [5,6]! In fact, explanations that are based on physical asymmetries can only predict an enantiomeric excess of one handedness over another, and not the 100% effect observed in nature [7].…”

Ionizing Radiation and Life

“…These include the destruction rate of amino acids (Kminek and Bada, 2006), racemization of an amino acid enantiomeric excess (Bonner, 2000, and references therein), alteration of biogenic organics (Court et al, 2006), nuclear reactions that lead to the loss of 13 C/ 12 C isotopic bias (Pavlov et al, 2002), and biopolymer fragmentation (Pavlov et al, 2002). The general issue is that after millennia of cosmic irradiation it may be difficult to distinguish between breakdown debris of unambiguous biomolecules, a valid signature of extinct life, and simple abiotic organic species created in situ by prebiotic chemistry or exogenously delivered by meteoritic or cometary infall.…”

“…For example, the polarization of electrons released by beta decay of radionuclides has been suggested as a causative agent in selecting the enantiomer bias by preferential synthesis or degradation of either enantiomer in an initially racemic mixture. However, systematic reviews of the varied experimental approaches attempted to demonstrate such an effect have concluded that there is no substantiating evidence for such a causal connection between nuclear parity violation and selection of an enantiomer bias in biomolecules (reviewed in Bonner, 2000, andFitz et al, 2007). A more recent alternative hypothesis posits that supernovae in the vicinity of the ISM from which the Solar System condensed were responsible for the generation of the observed bias toward L-amino acids in carbonaceous chondrite meteorites.…”

Opportunities for chiral discrimination using high harmonic generation in tailored laser fields

“…The complexity and variety of interactions and occurrences in nature of different enatiomers, flowing from such a small difference in their structure, is amazing. Chiral nature of living matter poses both fundamental and practical questions, from the origins of homochirality in biomolecules [1] to detection and manipulation [2] of chiral properties. The oldest method used to detect chirality in such media is optical rotation: the polarization plane of a linearly polarized light propagating through left and right chiral media rotates in opposite directions (see e.g.…”