The findings of Cronin and Pizzarello are probably the first demonstration that there may be natural processes in the cosmos that generate a preferred amino acid handedness, Jeffrey Bada of the Scripps Institution of Oceanography, La Jolla, Calif., said at the time.
The new PNAS work was made possible by the finding in Antarctica of an exceptionally pristine meteorite. Antarctic ices are good curators of meteorites. After a meteorite falls -- and meteorites have been falling throughout the history of Earth -- it is quickly covered by snow and buried in the ice. Because these ices are in constant motion, when they come to a mountain, they will flow over the hill and bring meteorites to the surface.
Thanks to the pristine nature of this meteorite, we were able to demonstrate that other extraterrestrial amino acids carry the left-handed excesses in meteorites and, above all, that these excesses appear to signify that their precursor molecules, the aldehydes, also carried such excesses, Pizzarello said. In other words, a molecular trait that defines life seems to have broader distribution as well as a long cosmic lineage.
This study may provide an important clue to the origin of molecular asymmetry, added Brown associate professor and co-author Huang.
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Arizona State University