The results of new research suggest a way to detect that a planet is on the threshold of the emergence of life.
A team made up of, among others, Vikas Nanda and Jennifer Timm, from Rutgers University in the United States, has made an important discovery in the framework of their search for the most elementary possible set of chemical reactions that allow the existence of a metabolism, or In other words, the chemical support of life. This set should have been the first to support life on Earth and probably can be so on other worlds as well. Nanda and his colleagues have identified part of a protein that can mark the aforementioned threshold of the appearance of life.
The results of the new study show that modern enzymes, despite their enormous complexity, probably evolved from very simple precursor peptides on the early Earth.
Everything points to the fact that one of the most likely chemical candidates to start life was a very simple peptide with two nickel atoms, which Nanda and his colleagues call “Nickelback” not because it has to do with the Canadian rock group of that name. , but because the nitrogen atoms of its “backbone” bond with the two nickel atoms. A peptide is a protein constituent made of a few amino acids, which are elementary biochemical building blocks.
The scientific community believes that between 3.5 billion and 3.8 billion years ago a tipping point was triggered that initiated the shift from prebiotic chemistry (molecules before life) to living biological systems. Nanda and her colleagues believe the change was triggered by small precursor proteins that performed key steps in an ancient metabolic reaction. And they think they have found one of the integrative “pioneer peptides.”
The scientists who carried out the study are members of a team led from Rutgers University called ENIGMA, which is part of NASA’s astrobiology program. Researchers are trying to understand how proteins evolved to become the predominant catalyst for life on Earth.
When scanning the universe with telescopes and probes for signs of past, present, or emerging life, NASA scientists look for specific “biosignatures” known to be precursors of life. Peptides like Nickelback could become the new biosignature to look for to detect planets about to produce life, as emphasized by Nanda.
Nickelback is made up of 13 amino acids and binds two nickel ions.
This computer rendering of the Nickelback peptide shows the backbone nitrogen atoms (blue) linking two critical nickel atoms (orange). Scientists who have identified this part of a protein believe it may be a telltale sign for planets about to produce life. (Image: The Nanda Laboratory)
Nickel was an abundant metal in the early oceans. By binding to the peptide, the nickel atoms become powerful catalysts, attracting additional protons and electrons and producing hydrogen gas. Hydrogen was also more abundant on the early Earth and must have been a fundamental energy source for metabolic processes.
The study is titled “Design of a minimal di-nickel hydrogenase peptide”. And it has been published in the academic journal Science Advances. (Fountain: NCYT de Amazings)