Cyanide may have played key role in origin of life

For life to have started on Earth, there must have been a genetic molecule similar to DNA or RNA.

Hyderabad: The origin of life on earth continues to be a mystery. Paradoxical as it may seem, Cyanide may have played a pivotal role in the process. The earth was formed around 4.5 billion years ago, and the first single-celled life forms are thought to have appeared on earth around 3.8 billion years ago. It is believed that biochemical reactions, which eventually made life possible, occurred during the intervening period of 700 million years. Yet, the exact nature of those reactions remains a mystery even in the 21st century.

According to the findings of Zoe Todd, a graduate from Harvard University, and Dimitar Sasselov, the Phillips Professor of Astronomy and the director of Harvard’s Origins of Life Initiative, Cyanide may have played a key role in the process.

It is yet to be ascertained, whether genetic mechanisms or metabolic mechanisms originated first. As per the RNA-world hypothesis, RNA nucleotides must have been formed first, from sugars. The researchers from Harvard have found that simple sugars such as glycolaldehyde and glyceraldehyde may have been produced by the passage of ultraviolet light through a combination of copper and cyanide.

“We re-created an experiment conducted by Ritson and Sutherland, from Cambridge, UK, in 2012, under the conditions that would have been applicable to early-Earth. They were able to synthesise sugars using copper cyanide and UV light,” said professor Sasselov in his paper.

The original experiment used UV light sources that were too strong, and hence very different from the early Sun. Also, they used high concentrations of copper cyanide. The Earth did not receive UV light of such high wavelengths when it was born. It probably received wavelengths shorter than those received by its surface today.

Since photochemical reactions are generally wavelength-dependent, it is necessary to study prebiotic photochemistry at multiple wavelengths and fluxes relevant to prebiotic earth.

“We re-created their experiment with lower concentrations and solar-like UV light as filtered down to early earth’s surface. Surprisingly, with the lower concentrations, the synthesis was even more efficient,” said professor Sasselov. While reducing the wavelengths of the UV light used, the researchers also reduced the concentrations of cyanide and copper and tested various combinations. They passed the UV light through small amounts of cyanide and copper held in an airtight quartz container.

“We are working on applying the early Earth approach to the entire chemical pathway, which we hope will lead to us uncovering the origin of life. We hope that a better understanding will help glean life’s emergence on planet earth, as well as the possibility of the emergence of life on other planets,” concluded the professor.

( Source : Deccan Chronicle. )
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