Reactions for Life at the Ocean Surface
A new study supported in part by the NASA Astrobiology Program examines how atmospheric aerosols could have played a role in helping along chemical reactions relevant to the origins of life on the prebiotic Earth. The study focuses on the interface of ocean water and the air, where aqueous/organic droplets form naturally. The study suggests that these droplets could have helped to collect organic reactants at concentrations much higher than in the open ocean. This is notable because, at the time of life’s origins on Earth, aerosol environments at the surface of the oceans would have represented a vast environment in which prebiotic reactions could have occurred.
The study focuses on phosphorylation, which is the addition of a phosphoryl group to a molecule. Phosphorylation reactions play an important role in every living cell on Earth today. Put simply, phosphorylation can act as an on/off switch for the activity of molecules like proteins. Before the formation of life’s first cells, however, phosphorylation reactions would have had to occur in the open environment. This is a problem because, in the absence of biology, these reactions are thermodynamically unfavorable in water. Previous studies have shown that some molecules can perform phosphorylation in aqueous solutions, including the compound Diamidophosphate (DAP). Even so, DAP reactions happen very, very slowly.
The new study demonstrates that the rate of DAP reactions can be increased in an aerosol environment. In the paper, the team outlines a proof-of-concept study by which 6.5 to 10% of uridine was converted to uridine-2′,3′-cyclophosphate in less than an hour. To perform the experiments, researchers injected aerosols containing DAP into a reaction chamber and monitored the phosphorylation rates. The aerosol experiments showed an increase in reaction rates over studies performed with DAP alone.
The results indicate that aerosol environments could have indeed played a role in promoting important prebiotic reactions. This finding could be particularly relevant to environments on the early Earth where aerosols formed naturally, such as at the surface of the ocean, where phosphorylation reactions could occur despite the fact that conditions in the ocean as a whole were not favorable.
The study, “Prebiotic Phosphorylation of Uridine using Diamidophosphate in Aerosols,” was published in the journal Nature. The work was performed at the NSF/NASA Center for Chemical Evolution (CCE) at the Georgia Institute of Technology in Atlanta, Georgia. The CCE is a collaborative program supported by the National Science Foundation (NSF) and the NASA Astrobiology Program. This research is a critical part of NASA’s work to understand the Universe, advance human exploration, and inspire the next generation. As NASA’s Artemis program moves forward with human exploration of the Moon, the search for life on other worlds remains a top priority for the agency.
