A small protein molecule that scientists said is one of the most likely chemical candidates to have kickstarted life has been identified by them in an advance that could provide clues to detecting habitable planets beyond Earth.
The findings, published recently in the journal Science Advances, have important implications in the search for extraterrestrial life as it gives scientists a new clue to look for.
Researchers, including those from Rutgers University in the US, found a simple peptide molecule with two nickel atoms is one of the most likely molecules that sparked life on Earth.
They have called the short protein molecule “Nickelback” due to its backbone nitrogen atoms bonding with two nickel atoms.
“Scientists believe that sometime between 3.5 and 3.8 billion years ago there was a tipping point, something that kickstarted the change from prebiotic chemistry – molecules before life – to living, biological systems,” study co-author Vikas Nanda said in a statement.
“We believe the change was sparked by a few small precursor proteins that performed key steps in an ancient metabolic reaction. And we think we’ve found one of these ‘pioneer peptides’,” Dr Nanda said.
In the study, scientists hoped to understand how proteins evolved to become the predominant catalyst of life on Earth.
The research can help astronomers look for signs of past, present or emerging life, and for specific life signature molecules in other parts of the universe.
Researchers reasoned that an original chemical that sparked life would need to be simple enough to assemble spontaneously in the water bodies of early Earth, but the chemical also had to be sufficiently reactive.
They started by examining existing contemporary proteins known to be associated with metabolic processes and pared them down to their basic structure.
Scientists found that the best candidate was Nickelback – a peptide made of 13 amino acids that binds two nickel ions – as the element Nickel was also abundant in Earth’s early oceans.
When bound to the peptide, researchers said, the nickel atoms become potent catalysts.
“This is important because, while there are many theories about the origins of life, there are very few actual laboratory tests of these ideas. This work shows that, not only are simple protein metabolic enzymes possible, but that they are very stable and very active – making them a plausible starting point for life,” Dr Nanda added.
