Scientists Uncover Urea’s Secret Role in the Origin of Life

Researchers have developed a new way to observe chemical reactions in liquids, shedding light on reactions involving molecules such as urea that may have contributed to the evolution of life on Earth. The technology includes a special device that produces a fine liquid jet and X-ray spectroscopy, which allows scientists to study movements that occur in mere femtoseconds.

Scientists from ETH Zurich and the University of Geneva have developed a new technique that allows them to observe chemical reactions occurring in liquids at a very high temporal resolution. These changes enable them to track how molecules change in mere femtoseconds – in other words, in a few quadrillionths of a second.

This achievement builds on previous research by the same group, led by Hans Jakob Wörner, Professor of Physical Chemistry at ETH Zurich. That work produced similar results for reactions occurring in the gas field.

To extend their X-ray spectroscopy studies to liquids, the researchers had to design a device capable of producing a liquid jet with a diameter of less than one micrometer in a vacuum. This was important because if the jet was wider, it would absorb some of the X-rays used to measure it.

Pioneer of molecular biochemistry

Using the new method, researchers were able to gain insight into the processes that led to the emergence of life on Earth. Many scientists think that urea played an important role here. It is one of the simplest molecules that contains both carbon and nitrogen.

Moreover, it is possible that urea was present even when the Earth was very young, something that was suggested by a famous experiment carried out in the 1950s: The American scientist Stanley Miller created a mixture of those gases that are believed to have formed the first part of the planet. atmosphere and put us under thunderstorm conditions. This produced a series of molecules, one of which was urea.

According to current theories, urea could have been enriched in hot water – often called the primordial soup – on a non-living Earth. As the water in the soup overflows, the concentration of urea increases. With exposure to ionizing radiation such as cosmic rays, it is possible for this concentrated urea to produce malonic acid. acid through several steps of integration. Then, this may create the building blocks of RNA and DNA.

Why did this exact assignment happen?

Using their new method, researchers from ETH Zurich and the University of Geneva investigated the first step in this long series of chemical reactions to find out how a concentrated urea solution behaves when exposed to ionizing radiation.

It is important to know that the urea molecules in the concentrated urea solution are themselves in pairs, or what are known as dimers. As researchers have been able to show, ionizing radiation causes hydrogen atom within each of these dimers moving from urea molecule to another. This converts one urea molecule into a protonated urea molecule, and the other into a urea radical. The latter is very active chemically – it is reactive, in fact, it is possible to react with other molecules, thus forming malonic acid.

The researchers were able to show that this transfer of the hydrogen atom happens very quickly, it only takes about 150 femtoseconds, or 150 quadrillionths of a second. “It’s so fast that this reaction prevents all other reactions from happening,” says Wörner. “This explains why concentrated solutions of urea produce urea radicals instead of undergoing other reactions that can produce other molecules.”

Responses to fluids are very important

In the future, Wörner and his colleagues want to examine the next steps that lead to the formation of malonic acid. They hope this will help them understand the origins of life on Earth.

As for their new method, it can be widely used to observe the exact sequence of chemical reactions in liquids. “A large number of important chemicals occur in the liquid – not only all biochemical processes in the human body, but also many chemicals related to industry,” said Wörner. That is why it is so important that we now extend the scope of X-ray spectroscopy to high temporal resolution to include reactions in liquids.”

Reference: “Femtosecond proton transfer in urea solutions investigated by X-ray spectroscopy” by Zhong Yin, Yi-Ping Chang, Tadas Balčiūnas, Yashoj Shakya, Aleksa Djorović, Geoffrey Gaulier, Giuseppe Fazio, Robin Santra, Ludger Inhester, Jean -Pierre Wolf and Hans Jakob Wörner, 28 June 2023, Nature.
DOI: 10.1038/s41586-023-06182-6

Researchers from ETH Zurich and the University of Geneva were assisted in this work by colleagues from Deutsches Elektronen-Synchrron DESY in Hamburg, who performed the calculations required to interpret the measurement data.