Four billion years ago, the Earth was devoid of life and covered by a large ocean. Life emerged over the course of millions of years. Researchers have been trying to figure out how the molecule came together. A new set of chemical reactions that use cyanide, ammonia, and carbon dioxide are thought to be common on the early earth.
"We came up with a new paradigm to explain the shift from prebiotic to biotic chemistry," says Krishnamurthy, who is an associate professor of chemistry. The kind of reactions we've described are likely what happened on early earth.
In addition to giving researchers insight into the chemistry of the early earth, the newly discovered chemical reactions are also useful in certain manufacturing processes.
Krishnamurthy's group showed how cyanide could enable the chemical reactions that turn water into basic organic compounds. This one worked in a wide range of temperatures and pHs. The researchers wondered if there was a way to make more complex molecule that composes proteins.
The -keto acids are used in cells to create the amino acids. Evidence shows that -keto acids existed in the past. It is thought that before the advent of cellular life, the -keto acids must have been created from completely different aldehydes. The switch from aldehydes to -keto acids as the key ingredient for making amino acids has led to debate.
Krishnamurthy and his colleagues suspected that cyanide could be used to turn -keto acids into amino acids. Ammonia is a form of nitrogen that was present on the early earth. They found carbon dioxide through trial and error. They were able to see the formation of amino acids with this mixture.
Krishnamurthy says that it turned out to be simpler than they had thought. It sits there if you mix only the three acids. The reaction increases as soon as you add carbon dioxide.
The researchers think that the new reaction is more likely to be the source of early life than different reactions. Two sides of a debate about the importance of carbon dioxide to early life have been brought together by the research.
Krishnamurthy's group discovered that a part of the same reaction that makes up the soup is called orotate. It is possible that the primordial soup could have given rise to a large number of the key elements of life.
Krishnamurthy wants to probe what kind of chemistry can emerge from this mixture. Is it possible that amino acids begin to form small proteins? Is it possible that one of those genes could come back and make more of these acids?
Krishnamurthy is one of the authors of the study.
More information: Ramanarayanan Krishnamurthy, Prebiotic synthesis of α-amino acids and orotate from α-ketoacids potentiates transition to extant metabolic pathways, Nature Chemistry (2022). DOI: 10.1038/s41557-022-00999-w. www.nature.com/articles/s41557-022-00999-w Journal information: Nature Chemistry
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