Scientists carefully simulated conditions on Earth in the early part of its history, about 4.6 billion years agoin hopes of better understanding how amino acids created the first ingredients of life.
Together, amino acids form proteins that play many vital roles in organisms. This new study was designed to help establish why a specific group of 20 “canonical” amino acids are used over and over again to build proteins when there are so many more of these amino acids to choose from.
These 20 amino acids are believed to be made up of 10 “early” taken from the atmosphere and early Earth meteorite fragments, and 10 “later” added on top – but what the selection process for the Last 10 implies is unclear.
“You see the same amino acids in every organism, from humans to bacteria to archaea, and that’s because all things on Earth are connected through this tree of life that has an origin, an organism that was l ‘ancestor of all living beings’, said chemist Stephen Fried of Johns Hopkins University in Maryland. “We describe the events that shaped why this ancestor got the amino acids he got.”
Through a reconstruction of primordial protein synthesis, the researchers showed that ancient organic compounds would have favored the best amino acids to fold proteins, tailoring them to specific functions.
In other words, a process of evolution or natural selection was already underway at this point: it was not the most readily available amino acids that were selected, but the amino acids best suited for a particular job. .
Had other amino acids been selected as part of the core group billions of years ago, scientists have determined that the very building blocks of life would not have been as effective in building that life.
“Protein folding essentially allowed us to evolve before there was even life on our planet,” said Fried. “You could have evolution before you had biology, you could have natural selection for chemicals useful to life before there was even DNA.”
Molecules, including proteins, are thought to have begun assembling simple organisms about 3.8 billion years agoso there’s a part of Earth’s past history that scientists have been keen to examine.
The team behind the study suggests that the “lower” 10 amino acids, in particular, were selected for their protein folding abilities, allowing DNA replication and the production of proteins that gave birth to life.
This research can tell us more about the potential of microorganisms on other planets and on our own: the same amino acids that arrived on Earth via meteorites can also be found in many other places in the Universe.
“The universe seems to love amino acids” said Fried. “Maybe if we found life on another planet, it wouldn’t be so different.”
The research was published in the Journal of the American Chemical Society.