New Chemical Reactions Can Help Explain Origin of Life From Non-Living Molecules

The “origin of life” is a subject that scientists have invested an unparalleled amount of time and resources in to understand it better. How life emerged from non-living molecules continues to be a much-debated topic. But now, scientists at Scripps Research may have found something to shed light on the subject. Scientists have discovered a set of chemical reactions that can produce amino acids and nucleic acids — the building blocks of proteins and DNA — by using cyanide, ammonia, and carbon dioxide.

What makes this an important discovery? The compounds present in the reactions that can form the building blocks of proteins are also substances that were thought to be common on early Earth, the study published in the journal Nature Chemistry explains.

Ramanarayanan Krishnamurthy, the lead author of the paper published on July 28, said about the discovery, “We’ve come up with a new paradigm to explain this shift from prebiotic to biotic chemistry.” Krishnamurthy, who is an associate professor of chemistry at Scripps Research, added, “We think the kind of reactions we’ve described are probably what could have happened on early Earth.”

The discovery comes just months after Krishnamurthy’s group showed how cyanide could enable the chemical reactions that convert water and prebiotic molecules into basic organic compounds required to support life. The attempt was a success and one that worked across a wide pH range at room temperature. Following this development, scientists wondered if the same conditions would also allow the generation of amino acids, which are far more complex molecules that “compose proteins in all known living cells,” the research explained.

After cyanide, the team zeroed in on nitrogen, which is an essential compound in the chemical reaction. So, they added ammonia, a form of nitrogen present on the early Earth. Following a series of trial and error, they discovered carbon dioxide to be the third ingredient of the mixture that could form amino acids.

“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,” Krishnamurthy said. “We were expecting it to be quite difficult to figure this out, and it turned out to be even simpler than we had imagined.”

As the next step, the team will focus on “what kind of chemistry can emerge from this mixture” and whether the amino acids can start forming small proteins.


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Building Blocks of Life Discovered on Asteroid Located 200 Million Miles Away From Earth

Scientists have discovered the building ingredients of life on an asteroid in space for the first time. More than 20 amino acids have been identified on the space rock Ryugu, which is more than 200 million miles from Earth. Scientists studied materials taken from the asteroid by the Japan Aerospace Exploration Agency’s (JAXA) Hayabusa2 probe, which landed on Ryugu in 2018. The spacecraft retrieved 0.2 ounces (5.4 grams) of material from the asteroid’s surface and subsurface in 2019, stored it in an airtight container, and returned it to Earth. Ryugu is made up of several small boulders rather than a single huge boulder.

Ryugu is rich in carbon-rich organic stuff, much of which is thought to have come from the same nebula that gave birth to the Sun and the Solar System around 4.6 billion years ago. Water has also been found on the asteroid, according to previous sample research.

The pitch-black asteroid samples, which only reflect 2 to 3 percent of the light that touches them, have not been modified by interactions with Earth‘s environment, giving them a chemical makeup far closer to that of the early Solar System.

Geochemist Nicolas Dauphas, one of the three University of Chicago researchers who worked with the Japan-led team of scientists, said that they only had a few of these rocks to analyse earlier, and they were all meteorites that had been housed in museums for decades to centuries, changing their compositions. So, Dauphas added, it was remarkable to have immaculate samples from outer space because they are eyewitnesses from places of the solar system nobody has visited before.

Hiroshi Naraoka, a planetary scientist at Kyushu University and the leader of the team that looked for organic matter in the samples, said while outlining the findings at the Lunar and Planetary Science Conference in March that they found a variety of prebiotic chemical molecules in the samples, including proteinogenic amino acids, polycyclic aromatic hydrocarbons akin to terrestrial petroleum, and a variety of nitrogen compounds.

Sample analysis initially found 10 amino acid kinds, but the number has already risen to more than 20. Amino acids are the basic building blocks of all proteins and are required for life to exist on our planet.

The first collection of these findings, published in Science, reveals Ryugu’s makeup.

For now, the researchers are analysing Ryugu samples, and additional information about the asteroid’s makeup will be released soon.


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