Moisture absorbing minerals may have helped spark life on early Earth: Study

Washington (PTI): A type of mineral that dissolves in water absorbed from humid air may have assisted in the construction of proteins on the early Earth, according to a study that may have implications in understanding how the first living cells formed on our planet.

The study, published in the journal Nature Communications, noted that deliquescent minerals which absorb moisture from their surrounding atmosphere, may have helped form big polymer molecules important for life before natural biological reactions evolved to make them. Until now scientists believed that the building blocks of all proteins -- amino acids -- subjected to repeated wet-dry cycles may have cooked up peptides and proteins on early Earth where the hot sunny days were interrupted by occasional rainstorms, the study noted.

However, the researchers behind the current study, including those from Saint Louis University in the US, said that a major drawback to the theory was its reliance on unpredictable storms that may have watered-down the ingredients to excess. While the building blocks must dissolve in a liquid solution for constructive chemical processes to occur, the researchers said that too much water could lead to hydrolysis -- a process in which water breaks apart chemical bonds.

Too much water will eventually flood developing cells containing the premordial soup of biochemicals, pushing them out too far away from each other to react, the researchers said. The researchers said that an important piece of the puzzle is solved if the role of deliquescent salts in early Earth's biochemical reactions is considered. These minerals, the study noted, absorb a limited amount of water from the air, based on the humidity levels, and natural regulate the amount of water in a solution.

The researchers showed that deliquescent salts can assist making peptides from the simplest amino acid -- glycine -- in self-regulated, repeating wet-dry cyclic processes. The reaction mixtures formed peptides in the daytime when they evaporated to dryness at high temperatures. And at night, the researchers said that the reactions acquired water from the atmosphere to form aqueous solutions at low temperatures.

The excess moisture, the researchers said, re-wetted the reactants without the addition of water by a rainstorm -- avoiding the possibility of destructive over-dilution. When they changed the ambient humidity from 50 to 70 percent, they found profound differences in the tendency of samples to absorb water, and hence, large differences in the yields of reactions the minerals hosted. The study noted that while the two elements sodium and potassium are almost identical in terms of reactivities, potassium salts are more deliquescent whereas sodium is not.

The potassium salt 'K2HPO4' fostered ten times higher yield of peptides from glycine than in the sodium salt 'Na2HPO4'. The researchers mentioned that their system may provide clues relevant to solving the mystery of why all life on Earth spends a lot of energy enriching potassium inside cells, and throwing sodium out.