Symmetry 2010, 2(2), 1022-1032; doi:10.3390/sym2021022
Review

Origin of Homochirality of Amino Acids in the Biosphere

Shosuke Kojoemail
Department of Food Science and Nutrition, Nara Women’s University, Nara 630-8506 Japan
Received: 21 January 2010; in revised form: 28 April 2010 / Accepted: 10 May 2010 / Published: 13 May 2010
(This article belongs to the Special Issue Symmetry of Life and Homochirality)
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Abstract: Discussions are made concerning realistic mechanisms for the origin of L-amino acids in the biosphere. As the most plausible mechanism, it is proposed that a mixture of racemic amino acids in the prebiotic sea caused spontaneous and effective optical resolution through self crystallization, even if asymmetric synthesis of a single amino acid has never occurred without the aid of an optically active molecule. This hypothesis is based on recrystallization of a mixture of D,L-amino acids in the presence of excess of D,L-asparagine (Asn). The enantiomeric excess (ee) of each amino acid in the resulting crystals indicates that crystallization of co-existing amino acids with the configuration same as that of Asn took place, although it was incidental whether the enrichment occurred in L- or D-amino acids. In addition, the resulting ee was sufficiently high (up to 100%) to account for the predominance of L-amino acids on the earth.
Keywords: homochirality; L-amino acid; crystallization; chemical evolution; optical resolution; asymmetric synthesis; enantiomeric excess

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Cite This Article

MDPI and ACS Style

Kojo, S. Origin of Homochirality of Amino Acids in the Biosphere. Symmetry 2010, 2, 1022-1032.

AMA Style

Kojo S. Origin of Homochirality of Amino Acids in the Biosphere. Symmetry. 2010; 2(2):1022-1032.

Chicago/Turabian Style

Kojo, Shosuke. 2010. "Origin of Homochirality of Amino Acids in the Biosphere." Symmetry 2, no. 2: 1022-1032.

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