Primordial Soup: Scientists Discover New “Origins of Life” Chemical Reactions

Abstract Biochemistry Origin of life Concept

“We think the kind of reactions we’ve described are probably what could have happened on early Earth,” says Ramanarayanan Krishnamurthy.

The reaction generates the building blocks of proteins and DNA: amino acids and nucleic acids.

Four billion years ago, the Earth looked very different than it does today. It was devoid of life and covered by a vast ocean. Over the course of millions of years, life emerged in that primordial soup. For a long time, researchers have theorized how molecules came together to spark this transition. Now, scientists at Scripps Research have discovered a new set of chemical reactions that use ammonia, cyanide, and carbon dioxide—all thought to be common on the early Earth—to generate amino acids and nucleic acids, the building blocks of proteins and DNA.

“We’ve come up with a new paradigm to explain this shift from prebiotic to biotic chemistry,” says Ramanarayanan Krishnamurthy, PhD, and an associate professor of chemistry at Scripps Research. “We think the kind of reactions we’ve described are probably what could have happened on early Earth.” Krishnamurthy is the lead author of the new paper that was published in the journal Nature Chemistry on July 28, 2022.

In addition to giving scientists insight into the chemistry of the early Earth, the newly discovered chemical reactions are also useful in certain manufacturing processes. For example, in the generation of custom-labeled biomolecules from inexpensive starting materials.

Earlier this year, Krishnamurthy’s team showed how cyanide can enable the chemical reactions that turn prebiotic molecules and water into basic organic compounds required for life. This one worked at room temperature and in a wide pH range, unlike previously proposed reactions. The scientists wondered whether, under the same conditions, there was a way to generate amino acids, which are more complex molecules that compose proteins in all known living cells.

In cells today, amino acids are generated from precursors called α-keto acids using both nitrogen and specialized proteins called enzymes. Scientists have discovered evidence that α-keto acids likely existed early in Earth’s history. However, many researchers have hypothesized that before the advent of cellular life, amino acids must have been generated from completely different precursors, aldehydes, rather than α-keto acids, since enzymes to carry out the conversion did not yet exist. But that idea has led to debate about how and when the switch occurred from aldehydes to α-keto acids as the key ingredient for making amino acids.

After their success in using cyanide to drive other chemical reactions, Krishnamurthy’s group suspected that cyanide, even without enzymes, might also help turn α-keto acids into amino acids. Because they knew nitrogen would be required in some form, they added ammonia—a form of nitrogen that would have been present on the early Earth. Then, through trial and error, they discovered a third key ingredient: carbon dioxide. With this mixture, they quickly started seeing amino acids form.

“We were expecting it to be quite difficult to figure this out, and it turned out to be even simpler than we had imagined,” says Krishnamurthy. “If you mix only the keto acid, cyanide, and ammonia, it just sits there. As soon as you add carbon dioxide, even trace amounts, the reaction picks up speed.”

Because the new reaction is relatively similar to what occurs inside cells today—except for being driven by cyanide instead of a protein—it seems more likely to be the source of early life, rather than drastically different reactions, the scientists say. The research also helps bring together two sides of a long-standing debate about the importance of carbon dioxide to early life, concluding that carbon dioxide was key, but only in combination with other molecules.

In the process of studying their chemical soup, Krishnamurthy and his colleagues discovered that a byproduct of the same reaction is orotate, a precursor to nucleotides that make up DNA and RNA. This indicates that the same primordial soup, under the right conditions, could have given rise to a large number of the molecules that are required for the key elements of life.

“What we want to do next is continue probing what kind of chemistry can emerge from this mixture,” says Krishnamurthy. “Can amino acids start forming small proteins? Could one of those proteins come back and begin to act as an enzyme to make more of these amino acids?”

Reference: “Prebiotic synthesis of α-amino acids and orotate from α-ketoacids potentiates transition to extant metabolic pathways” by Sunil Pulletikurti, Mahipal Yadav, Greg Springsteen and Ramanarayanan Krishnamurthy, 28 July 2022, Nature Chemistry.
DOI: 10.1038/s41557-022-00999-w

In addition to Krishnamurthy, authors of the study, “Prebiotic Synthesis of α-Amino Acids and Orotate from α-Ketoacids Potentiates Transition to Extant Metabolic Pathways,” are Sunil Pulletikurti, Mahipal Yadav and Greg Springsteen. 

This work was supported by funding from the NSF Center for Chemical Evolution (CHE-1504217), a NASA Exobiology grant (80NSSC18K1300) and a grant from the Simons Foundation (327124FY19).

15 Comments on "Primordial Soup: Scientists Discover New “Origins of Life” Chemical Reactions"

  1. Hello, my name is Marcelo Jubilado Catharino, I studied everything that caused me chaos when I was in depression, so I understood how necessary it is for us to teach other humans to move in agreement with each other. But I don’t like the spotlight and high social status due to my living being satisfying with everyone I love, so I see that my greatest achievement has been living my life. This one that makes me understand and realize how necessary it is for me to remain with the achievements that I have already conquered, thus, I add the necessary values ​​according to the need of my own surroundings to live better in society. Because of this way of looking at life, I created 2 theories, a theory of 2 atoms in quantum motion in infinite singularity towards itself and in any direction. The other theory of 1 atom moving in singularity where we have the clock (time is the marking of the propagation of energy), zodiac symbols, star of David and other theories of the movement of itself. I explain both theories in my books _Chaos from the past being vivid in the future_ (quantum explanation) and _freedom within chaos_ (philosophy). Within these two theories, all theories fit, from Platonic archetypes, Fibonacci, time crystal (atoms being compressed until they are in singularity), quantum Darwinism, Tesla, Einstein, Socrates, all forms of religious capture and everything that contains movement. . In my theory I say that everything that contains matter, physics and everything that exists contains life. Soon I realize that the difference between us humans and anything that exists is to be able to interpret death, because everything that exists goes through chaos to adapt, within this chaotic adaptation contains “records” of DNA, gravity, forces, physics, quantum physics and all energies existing in the universe. When the beginning of the universe occurred, its origin had a great release of energy and that energy came from a great initial movement, what is the value of this initial movement and how long does it take for it to adapt? I soon see that that initial movement is the movement that controls the entire universe in adapting and staying in singularity. How much chaos is in the universe? Within these adaptation movements, what is the most powerful energy? universe, galaxy, solar system, earth or humans… Who needs to adapt, we humans or the universe adapt to us humans?

  2. There’s some men in suits outside that want to speak with you. Come quietly or there will be trouble.

  3. Robert A Hill | July 29, 2022 at 5:32 pm | Reply

    This is fascinating. Those who have followed abiogenesis know this is a key gap in materialistic philosophy, that is, no real theory of how life could arise from non-life. Those with faith that this (“spontaneous generation”) is possible have seen a lot of false starts. Of course, they say it took Edison 100 tries to find the right combination of vacuum containers, metal filaments and current to before he devised a working electric light bulb. I for one have a hard time seeing how the information in a closed system can increase (in this case very, very significantly), i.e., at random, but a lot can be learned even absent success.

    • Robert A Hill, “how the information in a closed system can increase…” Why do you think the whole earth was a closed system? Energy from the sun, wet/dry cycles in each day, rain and tides to refill evaporating ponds at the shore, volcanic eruptions, etc. LOTS of energy inputs all over the place! Then chemical reactions which began natural selection.

      • Torbjörn Larsson | July 31, 2022 at 10:02 am | Reply

        Erroneous claim on nature is all organized superstition such as creationism has. Meanwhile most people today have got an education instead.

    • Torbjörn Larsson | July 31, 2022 at 10:00 am | Reply

      Meaningless superstition such as yours has nothing to do with what we find in nature, nor are scientists using equally meaningless philosophic ‘materialism’. That’s all your imagination.

      But we now have scientific phylogenetic evidence of evolution all the way from the initial split between biology and geology. No imaginary magic needed:

      “Our earliest, ‘half-alive’ ancestor needed little boost from heat
      Life on Earth assembled itself in warm, mildly alkaline conditions, study says”

      “By looking at the genes bacteria and archaea share, the researchers reconstructed the genome of the last universal common ancestor (LUCA) of all living things, they reported in Nature Microbiology. Having LUCA’s genome was a key step in understanding how nonliving chemicals organized themselves into living organisms.”

  4. The origin of life is more than than making (or finding) amino acids. Those amino acids must get together to form peptide, nucleotide and polypeptide bonds needed to extend themselves to make proteins and eventually cells. None of that can be done in an ocean simply because that process needs the input of heat energy with the loss of water. On land that would subject all early experiments to the full impact of the young Sun’s UV radiation. Something else is needed.

    • Torbjörn Larsson | July 31, 2022 at 10:10 am | Reply

      Luckily no, considering Earth likely had a deep global ocean at firs. Dehydration reactions occur in the hydrothermal vents at the ocean bottom, and we have now seen all the requisite reactions.

      Lipid, sugar and nucleobase formation, nucleotide strand elongation and strand duplication in alkaline hydrothermal vents under mild non-equilibrium conditions that occur there. And all biological (and more) amino acids synthesized and even forming (random) peptides in very turbulent, hydrogen releasing acidic vents. The last part is actually harder, go figure – so finding easier deep ocean chemistry like the one reported here is a boon.

      This research is just a decade old, but it fits with what biology now find out on how geology – half alive cells – life evolved, see another of my comments here.

  5. And then there is the unimaginably complex problem of deriving DNA (with its requirement for homo-chirality) from what these scientists, no doubt, achieved in the lab (through intelligently guided chemical processes)–a racemic solution of very simple amino acids.

    And those who believe in an intelligence behind the creation of life are accused of taking a leap of faith?

    • Torbjörn Larsson | July 31, 2022 at 10:15 am | Reply

      Yes, creationism is superstition.

      Biological science evidence is that RNA evolved before DNA – the DNA genetic and metabolic core is RNA – and was heterochiral – there are two frozen in chiral filter in the genetic machinery giving 90 % selectivity which is unnecessary today. The heterochiral evolution fits with the newer evidence that let us track the initial split between biology and geology to evolution all the way, see another of my comments here for references.

  6. You need a whole lot more than Amino Acids to create life Atheists.. Homo Chirality just for starters…

    The Fairytale of Evolutionism is a Fraud..

    • Torbjörn Larsson | July 31, 2022 at 10:16 am | Reply

      Ah, identical creationism repeated. I should have checked for trolling first. Well, se my other comments for the science.

      You should really try with arguments that at least *look* new, even if they too of course has nothing to do with reality.

  7. My phone needs to stop recommending these to me before I form a god complex.

  8. Robert A Hill | August 4, 2022 at 4:26 pm | Reply

    Torbjörn, that Science article is interesting. Thanks. This is (to my uneducated eye) more or less the argument I have seen for (as you say) about ten years, i.e., that heat-generating reactions in a crevice eventually led to proto-RNA, then to cells with membranes, etc. (Lack of adequate time is a related issue, but you obviously think the time available was sufficient.) Am I to understand the thinking is that the process is *not* random, i.e., there is a tendency in the geochemistry for vastly increasing complexity in some subset thereof?

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