A team of Rutgers University scientists trying to pinpoint the primordial basis of metabolism — the basic set of chemical reactions that first started life on Earth — has discovered a protein fragment that could give scientists clues to the identification of planets. life. The study, published March 10 in the journal Science AdvancesIt’s important to the search for extraterrestrial life because it gives researchers a new clue to their search, said Vikas Nanda, a research associate at the Center for Advanced Biotechnology and Medicine (CABM) at Rutgers.

Based on lab work, Rutgers scientists say one of the most likely chemical candidates to start life is a simple peptide with two nickel atoms, which they named “Nickelback”, not because it had anything to do with a Canadian rock band. nitrogen base atoms bond two critical nickel atoms. A peptide is a component of a protein made up of several essential building blocks known as amino acids.

“Scientists believe that somewhere between 3.5 and 3.8 billion years ago, there was a tipping point, something that made the transition from prebiotic chemistry (molecules for life) to living biological systems,” Nanda said. “We believe the change was caused by a few small precursor proteins that performed important steps in an ancient metabolic reaction. And we think we’ve found one of these ‘precursor peptides’.

The scientists who conducted the research are part of a Rutgers-led team called The Evolution of Nanomachines in the Geosphere and Microbial Ancestry (ENIGMA), part of the Astrobiology Program at NASA. Researchers are trying to understand how proteins evolved to become the main catalyst for life on Earth.

NASA scientists examine the universe with telescopes and probes for signs of past, present, or future life, looking for specific “biosignatures” known to be harbingers of life. Nanda said peptides like Nickelback could be the latest biosignature used by NASA to detect planets that are on the verge of harboring life.

The researchers hypothesize that the original trigger chemical must have been simple enough to turn itself into a prebiotic soup. But it must be chemically active enough to have the potential to draw energy from the environment to initiate a biochemical process.

To do this, the researchers used a “reductionist” approach: They started by examining existing modern proteins known to be associated with metabolic processes. Knowing that proteins were too complex to emerge at an early stage, they reduced them to their basic structure.

After a series of experiments, the researchers concluded that Nickelback was the best candidate. The peptide consists of 13 amino acids and binds two nickel ions.

They believed that nickel was a common metal in the early oceans. When attached to the peptide, the nickel atoms become powerful catalysts, attracting additional protons and electrons and producing hydrogen gas. The researchers suggest that hydrogen was also more common on early Earth and may have been an important source of energy for metabolism.

“This is important because while there are many theories about the origin of life, there are very few real laboratory tests of these ideas,” said Nanda. “This work demonstrates that not only are simple protein metabolic enzymes possible, but they are also very stable and very active, making them a possible starting point for life.”