Prussian blue linked to origin of life

December 15th, 2009 - 2:33 pm ICT by ANI  

Washington, December 15 (ANI): In a new study, a team of scientists has shown that hydrogen cyanide, urea and other substances considered essential to the formation of the building blocks of life can be obtained from the salt Prussian blue.

A team of researchers from the Astrobiology Centre (INTA-CSIC) carried out the study.

In order to carry out this study, the scientists recreated the chemical conditions of the early Earth.

“We have shown that when Prussian blue is dissolved in ammoniac solutions, it produces hydrogen cyanide, a substance that could have played a fundamental role in the creation of the first bio-organic molecules, as well as other precursors to the origin of life, such as urea, dimethylhydantoin and lactic acid,” said Marta Ruiz Bermejo, lead author of the study.

Urea is considered to be an important reagent in synthesising pyrimidines (the derivatives of which form part of the nucleic acids DNA and RNA), and it has been suggested that hydantoins could be the precursors of peptides and amino acids (the components of proteins), while lactic acid is also of biological interest because, along with malic acid, it can play a role in electron donor-recipient systems.

The researcher and her team have proved that these and other compounds originate from the cyanide liberated by the salt Prussian blue when it is subjected for several days to conditions of pH12 and relatively high temperatures (70-150 degrees C) in a damp, oxygen-free ammoniac environment, similar to early conditions on Earth.

“In addition, when Prussian blue decomposes in this ammoniac, anoxic environment, this complex salt, called iron hexacyanoferrate, also turns out to be an excellent precursor of hematite, the most stable and commonly found form of iron oxide on the surface of the Earth,” explained Ruiz Bermejo.

The researchers have confirmed in other studies that Prussian blue can be obtained in prebiotic conditions (from iron ions in methane atmosphere conditions with electrical discharges).

The synthesis of this salt and its subsequent transformation into hematite offers an alternative model to explain the formation of the banded iron in abiotic conditions in the absence of oxygen.

According to Ruiz Bermejo, Prussian blue “could act as a carbon concentrator in the prebiotic hydrosphere, and that its wet decomposition in anoxic conditions could liberate hydrogen cyanide and cyanogen, with the subsequent formation of organic molecules and iron oxides”. (ANI)

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