Homochirality as the signature of life: the SETH Cigar.

A characteristic hallmark of life is its homochirality: all biomolecules are usually of one hand, e.g. on Earth life uses only L-amino acids for protein synthesis and not their D mirror images.

Parity violation and chiral symmetry breaking of a racemic mixture.

The chiral symmetry breaking of a racemic mixture by the parity violating weak interaction is considered. Particular attention is given to a mechanism recently proposed by Mason and Tranter whereby the weak neutral current interaction in chiral molecules leads to the differential absorption of unpolarized light by D vs. L enantiomers.

Amplification of chirality based upon the association of nucleic acid strands of opposite handedness.

It is proposed that nucleotide strands of opposite handedness may strongly associate and thereby provide the key step of a mechanism for the amplification of a small enantiomeric excess in an initially near-racemic mixture of poly- or oligonucleotides. This hypothesis, if confirmed by experimentation, may have important implications for the question of the origin of biomolecular chirality. The results of preliminary NMR experiments are given, which do show evidence of a strong association between pentanucleotide RNA strands whose monomers have opposite chirality.