GREENBELT, Md., March 17 (UPI) -- U.S. space agency scientists say they've discovered meteor dust contains clues to a long-standing mystery: how life works at its most basic, molecular level.
"We found more support for the idea that biological molecules, like amino acids, created in space and brought to Earth by meteorite impacts help explain why life is left-handed," said Daniel Glavin of the National Aeronautics and Space Administration's Goddard Space Flight Center. "By that I mean why all known life uses only left-handed versions of amino acids to build proteins."
Although life based on right-handed amino acids would presumably work fine, "you can't mix them," said Jason Dworkin, co-author of the study. "If you do, life turns to something resembling scrambled eggs -- it's a mess. Since life doesn't work with a mixture of left-handed and right-handed amino acids, the mystery is: how did life decide -- what made life choose left-handed amino acids over right-handed ones?"
The team of researchers analyzed samples of carbonaceous meteorites collected during the past four years, looking for the amino acid isovaline and discovering three types of carbonaceous meteorites had more of the left-handed version than the right-handed variety.
"Finding more left-handed isovaline in a variety of meteorites supports the theory amino acids brought to the early Earth by asteroids and comets contributed to the origin of only left-handed based protein life on Earth," said Glavin.
The study appears in the Proceedings of the National Academy of Sciences.
