Peptides are a type of molecule used in the formation of proteins and are made up of blocks of amino acids.
A laboratory study at Rutgers University found one of the molecules that could have triggered life on Earth. It is a peptide that they named “nickelback”, because its nitrogen atoms join two critical nickel atoms.
The discovery, published in the journal Science Advances, has relevant implications for research on extraterrestrial life because of the clue it provides experts.
“Scientists believe that sometime between 3.5 and 3.8 billion years ago there was a tipping point, something that led to the modification of prebiotic chemistry (molecules before life) in living biological systems,” Vikas said. Nanda, a researcher in Rutgers’ Department of Biochemistry and Molecular Biology.
“We think the change was initiated by a few small precursor proteins that played key steps in an ancient metabolic reaction. We think we found one of those pioneering peptides.”
Peptides are a type of molecule used in the formation of proteins and are made up of blocks of amino acids. The scientists in the group in charge of the study are part of a NASA team called Evolution of Nanomachine in Geospheres and Microbial Ancestors; their goal is to understand how proteins evolved to become the predominant catalyst for life on Earth.
Scanning the universe with telescopes and probes for signs of past, present, or emerging life, scientists often look for “bioprints” known to support life, so peptides like “nickelback” could be the new brand name used by NASA to detect planets about to produce it.
An original initiating chemical would have to be simple enough to assemble spontaneously in a primal soup, but would also have to be chemically active to have the potential to draw energy from its environment and drive a biochemical process.
They examined currently existing proteins known to be associated with metabolic processes. Knowing that these were too complex to have arisen in early stages, they reduced them to their basic structure. After various experiments, the scientists agreed that the best candidate was the so-called nickelback, made up of 13 amino acids and linked to two nickel ions.
The latter was an abundant metal in the primordial oceans. By binding to the peptide, the nickel atoms become powerful catalysts, attracting additional protons and electrons, as well as producing hydrogen gas.
“This is important because, although there are many theories about the origins of life, there is very little laboratory evidence for these ideas. This work shows that not only are metabolic enzymes possible, but also very stable and active, making them a plausible point of the beginning of life,” Nanda concluded.