A relatively simple protein model could answer one of the most important questions in science, how life arose. Such an answer would not only solve a problem that has plagued humanity for thousands of years and led to many creation stories, it could also aid the search for life on other planets.
All living things on earth rely on amino acids, often referred to as the “building blocks of life.” The presence of amino acids on meteorites suggests they were probably abundant on Earth when life began. However, the original spark of life also required energy, which was a catalyst to unite these building blocks.
A team looking for how life began on Earth reports their findings in a new paper, which they propose as a possible candidate.
“Scientists believe there was something that initiated the transition from prebiotic chemistry — molecules before life — to living, biological systems, when a critical point was reached between 3.5 and 3.8 billion years ago,” said study author Professor Vikas Nanda of Rutgers University. He explains: “We believe the change was fueled by a few small precursor proteins that performed important steps in an ancient metabolic reaction. And we think we’ve found one of these ‘pioneer peptides’.”
The molecule referred to here consists of two nickel atoms bonded by an amino acid backbone, which is why Nanda and his co-authors refer to this molecule as “Nickelback.” Nickel in this form can become a powerful catalyst, bringing together protons and electrons to form hydrogen, which can be an energy source.
Researchers think that the molecules at the beginning of life should have been simple, yet capable of providing energy for biochemical reactions. However, existing proteins are often too complex to meet these requirements, and so the team tried to turn them into a simpler molecule. Nickelback stands out as the most promising specimen they’ve ever found. Composed of 13 amino acids and two different nickel atoms, this molecule may not be enough to form a human, but the authors found that it is stable throughout the temperatures and acidities likely to be present at the time. As a result, once created, it could perform its role over and over again.
The abundance of nickel in early Earth’s oceans, combined with the possible presence of amino acids, makes it a likely possibility that nickelback existed at that time.
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