How life started on Earth? 'Missing link' that played vital role in origin of life discovered

A team of researchers has discovered a compound that may have played a vital role in the origin of life on Earth. Researchers in the US hypothesized that a chemical reaction called phosphorylation may have been crucial for the assembly of three key ingredients in early life forms.

They found ingredients which are made of short strands of nucleotides in a bid to store genetic information, short chains of amino acids (peptides) to do the main work of cells, and lipids to form encapsulating structures such as cell walls.

No one has ever found a phosphorylating agent that was plausibly present on early Earth and could have produced these three classes of molecules side-by-side under the same realistic conditions, researchers said. That compound is diamidophosphate (DAP).

"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 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," Krishnamurthy said.

From all over the world, scientists gathered to find likely routes for the epic journey from pre-biological chemistry to cell-based biochemistry.

"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.

Megha Karki, one of the researchers at TSRI revealed that DAP could phosphorylate each of the four nucleoside building blocks of RNA in water or a paste-like state under a wide range of temperatures and other conditions.

With the addition of the catalyst imidazole, a simple organic compound that was itself plausibly present on the early Earth, DAP's activity also led to the appearance of short, RNA-like chains of these phosphorylated building blocks.

"With DAP and water and these mild conditions, you can get these three important classes of pre-biological molecules to come together and be transformed, creating the opportunity for them to interact together," Krishnamurthy added