Could life on Earth start with a dose of cyanide?

In the course of history, cyanide deserves to be considered an extremely toxic substance. It was used as a biological weapon from the Franco-Prussian war in the late 1800s, through both World Wars, and some evidence supports its role in the Iran-Iraq war. It has even permeated popular culture, appearing in popular movies or comics when often used by secret agents, or people who are pondering the choice between betrayal and death.

The poison cyanide is quite common in popular culture, especially comic books.

But in a paper recently published in the journal Nature, a team of chemists suggests that although cyanide is often the end of life as we know it, it may have helped develop life since ancient times. early Earth, about 4 billion years ago. Back then, the world looked very different now. For example, the oxygen we breathe does not yet exist.

'Cyanide is toxic to the biological mechanisms we're studying today,' said Ramanarayan Krishnamurthy, a chemist at Scripps Research Institute in California and lead author of the study. can be non-toxic if nature knows how to handle it".

In the lab, he and the researchers essentially mixed together a bunch of molecules that were present on early Earth and then added some cyanide.

Ironically, the dangerous stuff has made it possible to synthesize the simplest components of life - under conditions of moderate reaction and relatively few steps. All surprisingly simple.

'That kind of thing scares you sometimes, when it's so simple,' says Krishnamurthy. 'We checked this by three or four different people to make sure we had the correct interpretations'.

The team says its unique mechanism marks the "first demonstration" of this kind of biological pathway to the origin of life - and a much simpler mechanism than the nontoxic one. , its widely accepted, requires harsh reaction conditions, complex steps, and trust.

What really happened 4 billion years ago?

We can't know what happened in the beginning, but.

Experts have long believed that in the early oceans of the Earth was a pot of "primordial soup", consisting of a container of many different molecules swirling continuously. And this "elemental stew" forced the molecules to interact and form complex compounds, which then mixed, and many steps later, resulting in simple organisms. This way then created everything, including us.

An important feature in this story is the reduced tricarboxylic acid cycle, or r-TCA cycle. This eight-step biological process uses proteins to form life-sustaining compounds. In short, it's considered essential to life today, so experts say it was likely important to life long ago, and disappeared in the primordial soup.

But the problem is that Earth's early environment was not ideal for r-TCA. Oxygen wasn't available when the Earth was so young, and neither were the proteins that drove the cycle. Scientists often say that certain metals can make things happen, but that requires extreme conditions, such as extreme heat.

Chemist Krishnamurthy explains that many of those conditions not only existed on the early Earth, but also prevented scientists from taking steps to replicate ancient r-TCA reconstructions in the lab. Chemists have to put everything together, apply conditions, wait and watch.

While such experiments produce r-TCA compounds, it is difficult to prove they actually come from the cycle. Essentially, it's unclear whether r-TCA actually occurred 4 billion years ago.

In an effort to demonstrate an alternative reduction cycle that produces life-starting compounds, Krishnamurthy conducted experiments with cyanide in place of the troublesome metals. Remarkably, he found that the molecules followed the same pathway as r-TCA, one step at a time, but with fewer overall phases and under much milder conditions.

It seems to tell the story of early Earth's life in a much easier, substantial way.

Even so, the researchers are looking at their results with just a grain of salt in the middle of the ocean. "Cyanide is thought to have been present on the early Earth, although there is no direct evidence for that as it is a reactive molecule that could have been consumed," said Krishnamurthy.

According to chemist Krishnamurthy, stop assuming biology and just look at how things are made in so many ways.

Krishnamurthy also draws an analogy in interpreting this concept.

Imagine bringing someone from a remote village who only knew how to build a house out of bricks and a few masons to New York City. They will marvel at the skyscrapers and will probably ask you how these metal towers were made.

What they don't know, of course, is that these skyscrapers aren't made of bricks and certainly not by a small group of construction workers. They are made from steel, using cranes and giant equipment.

'What we're looking at biologically, is this huge, beautiful building,' said Krishnamurthy. out".

According to him, if there was enough cyanide on the early Earth, life could very well be indebted to what we now accept as poison. And taking it a step further, if extraterrestrial beings exist on other planets, perhaps cyanide has also "got a hand in".

'We're wanting to let chemistry tell us how things work,' says Krishnamurthy. 'Rather than assuming we already know how biological processes work 4 billion years ago. No, obviously we don't know anything about that time."

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