View Full Version : Was the primordial soup a hearty pre-protein stew?

09-07-2017, 03:57 PM
Was the primordial soup a hearty pre-protein stew?
The evolutionary path to first proteins may have been paved with relatively easy, small steps


"How proteins evolved billions of years ago, when Earth was devoid of life, has stumped many a scientist. A little do-si-do between amino acids and their chemical lookalikes may have done the trick. Evolutionary chemists tried it and got results by the boatload"

"Ancestors of the first protein molecules, which are key components of all cells, could have been bountiful on pre-life Earth, according to a new study led by researchers at the Georgia Institute of Technology, who formed hundreds of possible precursor molecules in the lab. Then they meticulously analyzed the molecules with latest technology and new algorithms.

They found that the molecules, called depsipeptides, formed quickly and abundantly under conditions that would have been common on prebiotic Earth, and with ingredients that would have likely been plentiful.

And some of the depsipeptides evolved into new varieties in just a few days, an ability that, eons ago, could have accelerated the birth of long molecules, called peptides, that make up proteins."

"The new NASA-affiliated research adds to a growing body of evidence suggesting that the first polymers of life may have arisen in variations of daily processes still observed on Earth today, such as the repeated drying and refilling of pond water. They may not have all zapped into existence as a result of blazing cataclysms, an image often associated with the creation of the first chemicals of life."

"Scientists have long puzzled over how the very first proteins formed. Their long-chain molecules, polypeptides, can be tough to make in the lab under abiotic conditions."

"But complex molecules of life likely did not arise in one dramatic step that produced final products. That's the hypothesis that drives the research of Fernández and his colleagues at the NSF/NASA Center for Chemical Evolution, headquartered at Georgia Tech and based on close collaboration with the Scripps Research Institute."

"Instead, multiple easier chemical steps likely produced plentiful in-between products that were useful in subsequent reactions that eventually led to the first biopolymers. The depsipeptides produced in this latest study could have served as such a chemical stepping stone"

"To understand depsipeptides and the significance of the researchers' results, it's helpful to start by looking at peptides, which are chains of amino acids. When the chains get really long they are called polypeptides, and then proteins.

Living cells have machinery that reads instructions in DNA on how to link up amino acids in a specific order to build very specific peptides and proteins that have functions in a living cell. For a protein to have function in a cell, its polypeptide chains have to clump up like sticky yarn to form useful shapes.

Before cells and DNA existed on an Earth devoid of life, for polypeptides to form, amino acids had to somehow jostle together in puddles or on the banks of rivers or lakes to form chains. But peptide bonds can be tough to form, especially long chains of them."

Jay G. Forsythe, Anton S. Petrov, W. Calvin Millar, Sheng-Sheng Yu, Ramanarayanan Krishnamurthy, Martha A. Grover, Nicholas V. Hud, Facundo M. Fernández. Surveying the sequence diversity of model prebiotic peptides by mass spectrometry. Proceedings of the National Academy of Sciences, 2017; 201711631 DOI: 10.1073/pnas.1711631114

11-03-2017, 02:09 PM
This looks to be the same story New Scientist is reporting in this week's edition - I skimmed it in the supermarket but its behind a paywall online.

"“We can stop bullshitting about the origin of life,” says Loren Williams, a biochemist at the Georgia Institute of Technology in Atlanta. “We can see it.” What he and his colleagues are discovering is turning our view of life’s origins on its head..."