Scientists at the Scripps Research Institute in La Jolla announced Monday that they may have found a compound essential to the formation of life on earth.
Their work was based on a hypothesis that a chemical reaction called phosphorylation may have been crucial for the assembly of three key ingredients in early life forms — short strands of nucleotides to store genetic information, short chains of amino acids known as peptides to do the main work of cells, and lipids to form encapsulating structures such as cell walls.
However, no one has previously found a substance that was plausibly present on early Earth that could result in phosphorylation to produce the three classes of molecules side-by-side under the same realistic conditions, according to TSRI.
In a study published in the journal Nature Chemistry, TSRI chemists said that diamidophosphate, commonly known to scientists as DAP, could have been present in Earth’s early days and responsible for phosphorylation.
“We suggest a phosphorylation chemistry that could have given rise, all in the same place, to oligonucleotides, oligopeptides and the cell-like structures to enclose them,” said study senior author Ramanarayanan Krishnamurthy, associate professor of chemistry at TSRI. “That in turn would have allowed other chemistries that were not possible before, potentially leading to the first simple, cell-based living entities.”
Previous theories centered on different phosphorylation agents for each process.
“It has been hard to imagine how these very different processes could have combined in the same place to yield the first primitive life forms,” said Krishnamurthy.
DAP, combined with water and mild ambient conditions can produce the three critical classes of pre-biological molecules, transform them and allow them to interact, he said.
“It reminds me of the Fairy Godmother in `Cinderella,’ who waves a wand and `poof, poof, poof,’ everything simple is transformed into something more complex and interesting,” Krishnamurthy said.
He said DAP’s phosphorylation chemistry closely resembles what is seen in the reactions at the heart of every cell’s metabolic cycle.
Krishnamurthy plans follow-up experiments and has teamed with early- Earth geochemists to try to identify potential sources of DAP, or similarly acting phosphorus-nitrogen compounds that were on the planet before life arose.
“There may have been minerals on the early Earth that released such phosphorus-nitrogen compounds under the right conditions,” he said. “Astronomers have found evidence for phosphorus-nitrogen compounds in the gas and dust of interstellar space, so it’s certainly plausible that such compounds were present on the early Earth and played a role in the emergence of the complex molecules of life.”
Funding for the research was provided by NASA and the Simons Foundation of New York.
—City News Service