According to a press release, Scripps Research scientists discovered a new set of chemical reactions that produce the building blocks of life using materials thought to be common in the primordial soup of early Earth.
The new discovery advances our understanding of how life flourished in the ancient past. It introduces a new, strong hypothesis for the origin of life on Earth, detailing the materials and reactions that may have occurred many years ago.
Investigating the origin of life
The first lifeforms on Earth are thought to have evolved billions of years ago in the primordial soup, a nutrient-rich mixture. The reactions required for life’s building blocks are thought to have occurred in part due to energy from hydrothermal vents.
The precise reactions that occurred during that time period are largely unknown, and they remain a major scientific mystery. The Scripps researchers developed their own version of the primordial soup using materials thought to be abundant in the early stages of life on Earth. They discovered a new set of chemical reactions that could have resulted in the first life on Earth using relatively simple ingredients.
Cyanide, ammonia, carbon dioxide, and alpha-keto acids were used in the reactions. When the scientists combined these materials, they noticed that their mixture produced more amino acids, which are a necessary component of the molecules required for life.
“We expected it to be quite difficult to figure out, but it turned out to be even simpler than we had imagined,” said Ramanarayanan Krishnamurthy, the study’s lead author. “It just sits there if you mix only the keto acid, cyanide, and ammonia.” When even trace amounts of carbon dioxide are added, the reaction picks up-speed.”
The simplest is the preferred hypothesis
The scientists describe the roles of each of the materials in their mixture in a new paper published in Nature Chemistry. Living cells use alpha-keto acids to make amino acids today. Nitrogen, which is required for the conversion process, is provided by ammonia. The cyanide facilitates the conversion, while the carbon dioxide speeds-up the entire process.
The researchers also explain that their mixture closely resembles how amino acids are formed in living cells. The main difference is that in living cells, cyanide replaces enzymes — cyanide was thought to be present in the primordial soup, but enzymes would not have existed at that time. Because their process is simpler than other hypotheses, the scientists believe it is more likely to have occurred during the early stages of life formation on our planet.
“What we want to do next is keep probing to see what kind of chemistry can emerge from this mixture,” Krishnamurthy said. “Can amino acids begin to form small proteins?” Could one of those proteins reappear and start acting as an enzyme to make more of these amino acids?” The scientists will continue to study the chemical reactions that occur in their mixture in order to gain a better understanding of the processes that could have-been responsible for life on earth.