At a research lab in the city of Hefei, in southeastern China’s Anhui province, a team of scientists has managed to create amino acids – the building block of life – using only air and water.
The experiment in August could offer a new approach to eco-friendly chemical production, according to the researchers.
The research also indicated a potential for more complicated molecules, such as proteins, the project’s lead scientist Zeng Jie, from the University of Science and Technology of China (USTC), said on Monday.
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Amino acids, the fundamental components of proteins, play a crucial role in living organisms and the researchers were looking for another way to synthesise glycine – the simplest stable amino acid.
Traditional methods of synthesising glycine have relied heavily on petroleum-derived products such as aldehydes and cyanides. These methods not only consume a significant amount of energy but also produce substantial waste, leading to environmental pollution.
The elements carbon, nitrogen, hydrogen, and oxygen, essential for amino acids, can all be sourced from carbon dioxide, water, nitrogen and oxygen in the air.
In their study, researchers from USTC and the University of Electronic Science and Technology of China produced an electrochemical catalysis process that began with air, paving the way for an eco-friendly method of synthesising amino acids.
Many scientists believe that life on Earth originated through chemical reactions in clouds, with lightning providing the electricity to drive the synthesis of amino acids from air and water.
As the reactions became more complex, they eventually transformed non-living matter into complex life forms, according to this view.
In the Miller-Urey experiment of 1952, scientists at the University of Chicago simulated Earth’s primitive atmosphere by sealing water, methane, ammonia and hydrogen in a container and applying electrical charges to mimic natural lightning.
After one week, they detected several amino acids in their final products, showing a potential origin for living molecules.
“The experiment simulated the generation of primitive life molecules, but the products were mixed, containing several amino acids,” Zeng said. “We have achieved the directional synthesis of single amino acids – glycine – through an innovative pathway design.”
The synthesis process consisted of three main parts: CO2 conversion, N2 fixation, and targeted C-N coupling.
First, carbon dioxide was converted into oxalic acid, then reduced to glyoxylic acid; nitrogen gas was synthesised into ammonia and then into hydroxylamine, which spontaneously reacted with the glyoxylic acid through electro-reduction to produce glycine.
Each step involved key catalysts and reaction devices. “The nitrogen fixation step, for instance, employed a lithium-mediated method that utilises the reactivity of metallic lithium to transform inactive nitrogen into lithium nitride, and subsequently into ammonia,” said Zeng, adding that the method was similar to how lithium batteries work through chemical reactions.
After less than a day of steady electrolysis, the research team was able to synthesise about 5.16 grams (0.18 of an ounce) of highly pure solid glycine in the lab using just air and water.
Zeng was very pleased with the results. “Typical organic synthesis reactions yield products in milligrams, but we made enough glycine to hold in the palm of your hand.”
The findings were published at the end of August in the peer-reviewed journal, Angewandte Chemie International Edition.
The study not only supports theories about the origin of life but also provides an eco-friendly pathway for synthesis – no pollution is generated, and the energy efficiency throughout the process reached 5.9 per cent, which compares with typical 2 to 3 per cent efficiency for natural plant photosynthesis.
Zeng has also experimented with using carbon dioxide to chemically and biologically synthesise glucose.
“We chose glycine because of its simpler structure among amino acids. Our team might explore the synthesis of more complex amino acids from natural materials in the future,” he said.
“By combining glucose and amino acids, the most basic biological molecules, we have an opportunity to explore the synthesis of more complex biological molecules from scratch, which is of vital importance.”
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