Homochirality

Homochirality is the predominance of one molecular handedness within a set of chiral molecules. Life on Earth consistently uses L-amino acids in proteins and D-sugars in nucleic acids.

Origin of life: The emergence of living systems from nonliving chemistry. Homochirality is one of the unresolved chemical features that origin-of-life accounts must explain.
Chirality: The property of an object that makes it distinguishable from its mirror image by rotation and translation alone. Homochirality is a population-level pattern built from molecular chirality.
Stereochemistry: The study of the three-dimensional arrangement of atoms in molecules and its effects. Homochirality is a recurring stereochemical pattern in biological molecules.
Protein: A polymer of amino acids folded into a structure that performs biological functions. L-amino acid homochirality enables the stereochemical regularity of proteins.
Asymmetric autocatalysis: A reaction in which a chiral product catalyzes its own formation with the same handedness. It can amplify a small initial imbalance into strong enantiomeric excess.
Enantiomer: One of two stereoisomers that are nonsuperimposable mirror images of each other. A homochiral set overwhelmingly favors one member of each enantiomeric pair.
Amino acid: An organic molecule containing amino and carboxyl functional groups; protein amino acids are linked into chains. Nearly all amino acids in ribosomally made proteins have the L configuration.
DNA: A double-stranded nucleic acid that stores hereditary information in most organisms. Its sugar-phosphate backbone is built from D-deoxyribose.
Circularly polarized light: Light whose electric field rotates as the wave propagates, with a defined left or right sense. Its unequal interaction with enantiomers could create a small chemical handedness bias.
Enantiomeric excess: The excess proportion of one enantiomer over the other, expressed relative to their total amount. It quantifies how strongly a sample departs from an equal mixture.

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