A team of scientists from the Boise State University and NASA have discovered carbon-rich meteorites which hold the key to life on early Earth. Although cyanide and carbon monoxide is fatal for humans, compounds containing iron and cyanide may have instigated life on earth.
According to reports, the alien compounds present in the meteorites are similar to the active site of hydrogenases. These are enzymes responsible for providing energy to bacteria and archaea, as a result of breaking down of hydrogen gas (H2). It was this detection that led to the realization that such compounds were present on the early earth, at a time when life began. This was such a time when the planet was attacked by meteorites and when the atmosphere was hydrogen-rich.
As per a statement by Dr. Karen Smith, who is a senior research scientist at the Boise State University, cyanide a carbon atom bound with nitrogen atom was a crucial element in building molecules which were essential for the formation of life on earth. This is especially possible as a result of non-biological synthesis of organic compounds, amino acids, and nucleobases, for instance. These are allegedly used by all life forms to build blocks of nucleic acids and proteins.
By means of analytical methods, the team of experts could measure ancient traces of cyanide in meteorites. Through this method, the scientists found that such meteorites which contain cyanide belong to the group of CM chondrites, which are carbon-rich meteorites. The team also found Martian meteorite, a type which has no cyanide.
Although previous discoveries in meteorites have found cyanide in meteorites, this study proved that cyanide was present along with carbon monoxide (CO), a binding component with iron, in order to form stable compounds in the meteorites. Through high-resolution liquid chromatography-mass spectrometry, the scientists also discovered iron cyano-carbonyl complexes in two different forms. These resemble active sites of hydrogenases which have a distinct structure.
Furthermore, Hydrogenases are present in modern bacteria and archaea, originating from ancient times. Although hydrogenases are large proteins, the region where the chemical reaction takes place, is much smaller. It is a metal-organic compound within the protein. This compound is similar to the cyanide-bearing compounds the scientists discovered in the meteorites.
“Cyanide and carbon monoxide attached to a metal are unusual and rare in enzymes. Hydrogenases are the exception. When you compare the structure of these iron cyano-carbonyl complexes in meteorites to these active sites in hydrogenases, it makes you wonder if there was a link between the two,” according to Smith. “It’s possible that iron cyano-carbonyl complexes may have been a precursor to these active sites and later incorporated into proteins billions of years ago. These complexes probably acted as sources of cyanide on early Earth as well.”
The research published in Nature Communications thus studies the mystery of how biology could have evolved from non-biological chemical processes.