A Computer Rendering of Nickelback Peptide Shows Nitrogen Atoms (blue) Bridging Two Critical Nickel Atoms (orange). – THE NANDA LABORATORY
At Rutgers University, a protein component has been identified that may provide scientists with clues to detecting life-producing planets.
According to Vikas Nanda, a researcher at Rutgers’ Center for Biotechnology and Medicine (CABM), the research published in Science Proceedings has important implications for the search for extraterrestrial life, as it provides researchers with a new lead in the search.
Based on studies at the Rutgers laboratory, scientists say that one of the most likely chemical candidates for the beginning of life was simple with two nickel atoms, which they call “Nickelback”, which has nothing to do with the rock band. Nitrogen atoms join two critical nickel atoms in their backbone. A peptide is a protein made up of a few basic building blocks known as amino acids.
“Scientists believe that between 3.5 and 3.8 billion years ago there was a tipping point that began the change from prebiotic chemistry – molecules that predate life – to living, biological systems,” Nanda explains in a statement. “We think that the change is triggered by a serval precursor that provided a key step in an ancient metabolic reaction. And we think that we have found one of these ‘pig-in’ peptides.’
The scientists conducting the study are part of a Rutgers-led team called Evolution of Nanomachines in Geospheres and Microbial Majors (ENIGMA), which is part of NASA’s Astrobiology program. Researchers are trying to understand how proteins evolved to become the main catalyst for life on Earth.
By looking at the universe with NASA telescopes and looking for signs of past, present or emerging life, scientists are looking for specific “biosignatures” known to be precursors of life. Peptides like nickelback have become the latest biomarkers used by NASA to detect life-producing planets, according to Nanda.
The researchers devised an original chemical recipe that would be simple enough to fit into a prebiotic soup. But it must be active enough to have the chemical potential to release energy from the environment for the biochemical process.
To this end, the researchers took a “reductionist” approach: They began to examine existing contemporary proteins known to be associated with metabolic processes. Knowing that proteins were too complicated before they arose, they reduced them to their basic structure.
After several subsequent experiments, the researchers came to the conclusion that Nickelback was the best candidate. The peptide is made of 13 amino acids and binds two nickel ions.
Nickel is thought to have been an abundant metal in the early oceans. By binding to the peptide, the nickel atoms become powerful catalysts that attract additional protons and electrons and produce hydrogen gas. Hydrogen, the researchers reasoned, was even more abundant on early Earth and would have been a critical energy source for fueling metabolism.
“This is interesting because, while there are many theories about the origins of life, there is very little laboratory evidence for these ideas,” Nanda said. “This work demonstrates that not only are simple protein-metabolizing enzymes possible, but they are highly stable and highly active, making them a likely source for life.”