ScienceDaily (Dec. 15, 2009) — A team of researchers from the Astrobiology Centre (INTA-CSIC) has shown that hydrogen cyanide, urea and other substances considered essential to the formation of the most basic biological molecules can be obtained from the salt Prussian blue. In order to carry out this study, published in the journal Chemistry & Biodiversity, the scientists recreated the chemical conditions of the early Earth.
This is Prussian blue. This salt could cause substances essential for life. (Credit: Nagem R.)
"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," Marta Ruiz Bermejo, lead author of the study and a researcher at the Astrobiology Centre (CSIC-INTA), said.
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 (the name of which refers to the dye used in the uniforms of the Prussian Army) when it is subjected for several days to conditions of pH12 and relatively high temperatures (70-150ºC) in a damp, oxygen-free ammoniac environment, similar to early conditions on Earth. The results of the study have been published recently in the journal Chemistry & Biodiversity.
"In addition, when Prussian blue decomposes in this ammoniac, anoxic environment, this complex salt, called iron (III) hexacyanoferrate (II), also turns out to be an excellent precursor of hematite, the most stable and commonly found form of iron (III) oxide on the surface of the Earth," explains Ruiz Bermejo.
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Journal Reference:
Ruiz-Bermejo et al. Thermal Wet Decomposition of Prussian Blue: Implications for Prebiotic Chemistry. Chemistry & Biodiversity, 2009; 6 (9): 1309 DOI: 10.1002/cbdv.200900024
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