Perspective

Extraterrestrial Handedness?

Science  14 Feb 1997:
Vol. 275, Issue 5302, pp. 942-943
DOI: 10.1126/science.275.5302.942

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Summary

Biological systems exhibit molecular handedness: During biosynthesis, predominantly L amino acids rather than D amino acids are incorporated into proteins. The origins of this handedness remain puzzling. In his Perspective, Bada discusses results reported by Cronin and Pizzarello in the same issue (p. 951) showing a slight excess of L amino acids in a well-known extraterrestrial object, the Murchison meteorite. This finding suggests the existence of an enrichment process in cosmochemical environments and could possibly be the source of molecular handedness on Earth.