Abstract Biochemistry Origin of life Concept

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

“Nous pensons que le type de réactions que nous avons décrites sont probablement celles qui auraient pu se produire sur la Terre primitive”, déclare Ramanarayanan Krishnamurthy.

La réaction génère les blocs de construction des protéines et

ADN
L’ADN, ou acide désoxyribonucléique, est une molécule composée de deux longues chaînes de nucléotides qui s’enroulent l’une autour de l’autre pour former une double hélice. C’est le matériel héréditaire des humains et de presque tous les autres organismes qui porte les instructions génétiques pour le développement, la fonction, la croissance et la reproduction. Presque toutes les cellules du corps d’une personne ont le même ADN. La majeure partie de l’ADN se trouve dans le noyau de la cellule (où il est appelé ADN nucléaire), mais une petite quantité d’ADN peut également être trouvée dans les mitochondries (où il est appelé ADN mitochondrial ou ADNmt).

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“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

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

This work was supported by funding from the NSF Center for Chemical Evolution (CHE-1504217), a

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