Chiral molecules have been seen in space for the first time ever, astronomers report. These prebiotic molecules are essential to life, and this finding could help explain how the spark of life was ignited here on Earth, far in the distant past.
Sagittarius B2(N), a nebula sitting 28,000 light years from Earth, was examined by astronomers searching for the tell-tale fingerprints of molecules tumbling in the gas. Each variety of molecule tumbles in a distinct fashion, based on its composition and arrangement of atoms.
Propylene oxide, a component of polyurethane foams, was discovered for the first time ever outside the solar system within the structure of the nebula. Although this study does reveal the presence of each form of molecule, it does not enumerate the quantity of each variety. Propylene oxide molecules are fairly small compared to many other organic materials found in the biological organisms. This chemical is not directly used in living systems, but finding this molecule outside the solar system suggests other chiral molecules are also likely to be found in nebula and other interstellar bodies.
Chiral molecules are pairs of these groups having the same number and type of atoms within their makeup, but arranged in mirror images of each other. This is similar to the way human hands each have a thumb, index finder, pinkie, etc., but they only match up palm-to-palm, as if each was seen in a mirror. Because of this, chiral molecules are known as being left- and right-handed.
Life processes are extremely dependent on the handedness of different forms, or enantiomers, of molecules. For instance, grapes utilize strictly left-handed variation of tartaric acid, while all life forms use right-handed ribose during body processes.
"How did it come to be that all living things use one enantiomer of a particular amino acid, for example, over another? If we could run the tape of life again, would the same enantiomers be selected through a deterministic process, or is a random choice made that depends on a tiny imbalance of one handedness over the other?" asked Geoffrey Blake of the California Institute of Technology (CIT).
Biologists are still uncertain why life would chose to use molecules posing handedness qualities, while it would seem accepting both forms of chemicals would be advantageous to life. This finding also brings another question to the forefront of the minds of astronomers. Once life is found on other planets and moons, will those lifeforms also utilize right- and left-handed molecules?
Detection of chiral molecules in Sagittarius B2(N) and analysis of the finding is set to be published in the journal Science on June 17.