Important key to life before its origin on Earth discovered

February 29th, 2008 - 1:02 pm ICT by admin  

Washington, Feb 29 (ANI): Researchers have discovered an important key to life before its origin on Earth, with the finding that some of the possible abiotic precursors to the origin of life on the planet have been shown to carry handedness in a larger number than previously thought.

Carried out by Sandra Pizzarello, a research professor at Arizona State University, the new research was done by 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.

The new research 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, 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, said Pizzarello.

In other words, a molecular trait that defines life seems to have broader distribution as well as a long cosmic lineage, he added.

This study may provide an important clue to the origin of molecular asymmetry, said co-author Huang. (ANI)

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