Scientists from Rutgers University have discovered evidence that simple protein catalysts—primordial peptides—could have existed when life ultimately began.
The researchers modeled a short, 12-amino-acid protein on a computer and after testing the model in the lab, found that the very peptide contains just two types of amino acids—rather than the estimated 20 amino acids that synthesize millions of different proteins needed for specific body functions.
The researchers believe this type of peptide could have emerged spontaneously on the early Earth with the right conditions.
The metal cluster at the core of the peptide is similar to the structure and chemistry of iron-sulfur minerals that were abundant in early Earth oceans. The peptide can also charge and discharge electrons repeatedly without falling apart.
“Modern proteins called ferredoxins do this, shuttling electrons around the cell to promote metabolism,” senior author Professor Paul G. Falkowski, who leads Rutgers’ Environmental Biophysics and Molecular Ecology Laboratory, said in a statement. “A primordial peptide like the one we studied may have served a similar function in the origins of life.”
The researchers now plan to continue studies to understand exactly how protein catalysts evolved at the start of life and characterize the full potential of the primordial peptide. They also plant to develop other molecules that could have played crucial roles in the origins of life.
In the late 1980s and early 1990s, chemist Günter Wächtershäuser postulated that life began on iron- and sulfur-containing rocks in the ocean. Wächtershäuser and others predicted that short peptides would have bound metals and served as catalysts of life-producing chemistry.
Human DNA is comprised of genes that code for proteins that are a few hundred to a few thousand amino acids long. Life likely began with simple proteins that were just 10-to-20 amino acids long. However, throughout history these proteins evolved to the more complex proteins that enables living things today to function properly.
With computers, Rutgers scientists have smashed and dissected approximately 10,000 proteins and pinpointed four “Legos of life”—core chemical structures that can be stacked to form the innumerable proteins inside all organisms. The recently discovered peptide could be a precursor to the longer Legos of life and scientists could study how the peptides functioned in early-life chemistry.
The study was published in the Journal of the American Chemical Society.