Print Edition: March 13, 2013
A team of chemists from the University of California, Berkeley and the University of Hawaii in Manoa have recently discovered that under the right conditions, complex molecules called dipeptides can be formed in space. Dipeptides are linked pairs of amino acids essential to our bodies, making up muscle and brain tissue in humans and other mammals. They are essential to all life on Earth, so what would it mean if these organic molecules can be found in space?
The chemists have evidence to believe complex dipeptides, proteins and enzymes can be created in the icy, interstellar space dust commonly found in comets. They conducted an experiment to simulate a comet in space and found the organic residue it produced revealed the presence of some of these organic molecules.
Seol Kim and Ralf Kaiser from the Hawaii team simulated a snowball in space—including carbon dioxide, ammonia and various hydrocarbons such as methane, thane and propane—in a vacuum chamber chilled to 10 degrees above absolute zero. The team then zapped the snowball with high-energy to simulate how cosmic rays affect objects in space. They found that the chemicals in the produced residue reacted to form all sorts of complex organic compounds, specifically dipeptides.
“It has been known that amino acids can be formed by ionizing radiation, so what we were trying to do is use these simple molecules, irradiate them, and see if biologically significant molecules could be formed,” Kaiser said in an interview with Marcie Kagawa for Star Advertiser News.
When the residue was further examined in California, the analysis revealed the presence of nine different amino acids and at least two dipeptides. Richard Mathies and Amanda Stockton used the Mars Organic Analyzer, an ultrasensitive instrument that Mathies designed for detection and identification of small organic molecules in the solar system. The amino acids found are capable of catalyzing biological evolution on Earth, but Kaiser is still skeptical about whether complex amino acids that are formed in space can be delivered to Earth. In the same interview with Kagawa, he noted that “there has been no consensus that the amino acids, once delivered to Earth, could form dipeptides or more complex polypeptides since these amino acids are likely too diluted in the ocean.”
Organic molecules have been discovered on various meteorites that have fallen to Earth in the past, but scientists have been unable to find the complex structures required in the planet’s biology on such cosmic entities.
Kaiser said this new evidence “might change the thinking that dipeptides can be directly seeded to Earth from outer space.”
This discovery definitely opens up the possibility that organic molecules were brought to Earth a long time ago, and that they helped in the formation of enzymes and sugars essential to life.
“It is fascinating to consider that the most basic biochemical building blocks that led to life on Earth may well have had an extraterrestrial origin,” Mathies said to Robert Sanders, journalist for Phys Organization.