TEMPE, ARIZ. -- An important discovery has been made with respect to the mystery of handedness in biomolecules. Researchers led by Sandra Pizzarello, a research professor at Arizona State University, found that some of the possible abiotic precursors to the origin of life on Earth have been shown to carry handedness in a larger number than previously thought.
The work is being published in this weeks Early Edition of the Proceedings of the National Academy of Sciences (PNAS). The paper is titled, Molecular asymmetry in extraterrestrial chemistry: Insights from a pristine meteorite, and is co-authored by Pizzarello and Yongsong Huang and Marcelo Alexandre, of Brown University.
Pizzarello, in ASUs Department of Chemistry and Biochemistry, worked with Huang and Alexandre in studying the organic materials of a special group of meteorites that contain among a variety of compounds, amino acids that have identical counterparts in terrestrial biomolecules. These meteorites are fragments of asteroids that are about the same age as the solar system (roughly 4.5 billion years.)
Scientists have long known that most compounds in living things exist in mirror-image forms. The two forms are like hands; one is a mirror reflection of the other. They are different, cannot be superimposed, yet identical in their parts.
When scientists synthesize these molecules in the laboratory, half of a sample turns out to be left-handed and the other half right-handed. But amino acids, which are the building blocks of terrestrial proteins, are all left-handed, while the sugars of DNA and RNA are right-handed. The mystery as to why this is the case, parallels in many of its queries those that surround the origin of life, said Pizzarello.
Years ago Pizzarello and ASU professor emeritus John Cronin analyzed amino acids from the Murchison meteorite (which landed in Australia in 1969) that were unknown on Earth, hence solving the problem
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Arizona State University