New study reveals additional insights into this mystery

Jul 26, 2012 07:41 GMT  ·  By
A complex interplay of factors may have controlled chirality in early molecules
   A complex interplay of factors may have controlled chirality in early molecules

A collaboration of scientists from NASA and various universities announces that a recent study conducted on meteorite samples collected from a Canadian lake provided new insights into the reason why life on Earth appears to prefer a certain chirality.

The last-named is a property of molecules dealing with their orientation, or handedness. The building blocks of all lifeforms on the planet are made up of left-handed components, and scientists have been wondering why that is for many years.

This specific orientation appears to support the development of life, experts say. Most amino acids, the building blocks of proteins, are left-handed, making us display a preference for this orientation as well. Interestingly, this also makes it more difficult for astrobiologists to discover alien life.

Meteorites discovered in Tagish Lake also featured chiral molecules. According to Dr. Daniel Glavin, the lead author of the new study, the space rocks provided a potential explanation for why proteins are made up exclusively of left-handed amino acids.

Glavin holds an appointment as a research scientist at the NASA Goddard Space Flight Center (GSFC), in Greenbelt, Maryland. He says that the new study is published in the latest issue of the journal Meteoritics and Planetary Science.

“Our analysis of the amino acids in meteorite fragments from Tagish Lake gave us one possible explanation for why all known life uses only left-handed versions of amino acids to build proteins,” the investigator explains.

These particular meteorites are different from others recovered on Earth through the fact that they were recovered from the Canadian lake within days of exploding into our planet's atmosphere, in 2000. This allowed scientists to preserve the rocks in their frozen state, with minimal contamination.

“This latest study gives us a glimpse into the role that water percolating through asteroids must have played in making the left-handed amino acids that are so characteristic of all life on Earth,” explains Dr. Christopher Herd, who is based at the University of Alberta, in Edmonton, Canada.

It is also interesting to note here that synthetic proteins made up of both right- and left-handed amino acids simply do not function, the director of the GSFC Astrobiology Laboratory, Dr. Jason Dworkin, explains.

The left-handed orientation found inside the meteorites may have been triggered by interplay of factors, including polarized radiation in the solar nebula, crystallization and dissolution. Only a tiny excess of left-handed molecules may have existed at first, but then got significantly amplified.