Comets like Halley’s can be a breeding ground for complex molecules such as dipeptides. Comets colliding with Earth could have delivered these molecules and seeded the growth of more complex proteins and sugars necessary for life. Credit: NASA.
Those wispy worlds of ice know as comets may be linked to kick-starting life on Earth.
Experiments by chemists from the University of California, Berkeley, and the University of Hawaii, Manoa, suggest that conditions in space are capable of creating complex dipeptides – linked pairs of amino acids. These are essential building blocks shared by all living things.
An experiment that simulated conditions in deep space has revealed that the complex building blocks of life could have been created on icy interplanetary dust and then carried to Earth, jump-starting life.
The research is outlined in an online paper due for print publication in The Astrophysical Journal.
University of California Berkeley chemist Richard Mathies, is coauthor of the paper.
“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 in a UC Berkeley press statement.
Snowball chemistry
The research opens the door to the possibility that dipeptides – linked pairs of amino acids — were brought to Earth aboard a comet or possibly meteorites, catalyzing the formation of proteins (polypeptides), enzymes and even more complex molecules, such as sugars, that are necessary for life.
In an ultra-high vacuum chamber chilled to 10 degrees above absolute zero (10 Kelvin), Seol Kim and Ralf Kaiser of the Hawaiian team simulated an icy snowball in space.
That snowball included carbon dioxide, ammonia and various hydrocarbons such as methane, ethane and propane. When zapped with high-energy electrons to simulate the cosmic rays in space, the chemicals reacted to form complex, organic compounds, specifically dipeptides, essential to life.
Complex molecules
At UC Berkeley, Mathies and Amanda Stockton then analyzed the organic residues through the Mars Organic Analyzer, an instrument that Mathies designed for ultrasensitive detection and identification of small organic molecules in the solar system.
The analysis revealed the presence of complex molecules – nine different amino acids and at least two dipeptides – capable of catalyzing biological evolution on Earth.
The research was supported by the National Science Foundation and the Mathies Royalty Fund at UC Berkeley.
The research paper is available at:
http://iopscience.iop.org/0004-637X/765/2/111/
By Leonard David via Robert Sanders/UC Berkeley