The traditional understanding of protein formation involves complex biological processes within cells. However, R. Graham Cooks, the Henry B. Hass Distinguished Professor of Chemistry, and his postdoctoral researcher Lingqi Qiu have uncovered experimental evidence challenging this long-held belief. Their recent publication in the Proceedings of the National Academy of Sciences presents a groundbreaking discovery – the key step in protein formation can occur within droplets of pure water. This unexpected finding has significant implications for the understanding of the origin of life on Earth.
Amino acids, the building blocks of proteins, are known to require dehydration (the loss of water) in order to connect and form peptides. However, a paradox arises when considering this process within a water solution. Cooks and Qiu’s research reveals that the surfaces of these droplets are unusually dry and highly acidic. This unique environment allows for the connection of amino acids and subsequent peptide formation, despite the presence of water. Remarkably, this process maintains the natural “left-handed” structure of amino acids, resulting in the formation of pure chiral peptides with the same “L” handedness.
The researchers identified a specific compound called oxazolidinone as a crucial intermediate in this reaction. Oxazolidinone plays a vital role in facilitating the dehydration process, allowing amino acids to connect and form peptides. Importantly, the dehydration reaction occurs not only at the microscopic level but also on a larger scale, as demonstrated in lab experiments starting from the oxazolidinone intermediate. This larger-scale reaction closely mirrors the microdroplet chemistry and resembles the wet-dry cycles observed in hydrothermal pools and seashores. This connection suggests that peptide formation occurs in both aerosols and extensive prebiotic environments.
The study conducted by Cooks and Qiu highlights the exceptional physical and chemical properties of water droplet surfaces. These surfaces exhibit very high electric fields and extreme acidity, which play a crucial role in driving the dehydration of amino acids and subsequent peptide formation. The chemistry occurring at the interfaces of water droplets provides valuable insights into the early stages of life’s chemical evolution. By expanding our understanding of the chemical processes that shape the building blocks of life, this research opens the door to new possibilities in the field of origin of life studies.
The authors extend their gratitude to Purdue research associates Dylan T. Holden and Nicolás M. Morato for their valuable discussions and contributions to this research.
The discovery of protein formation within water droplets challenges established theories about the origin of life. Understanding how amino acids can dehydrate and form peptides in the presence of water opens up new avenues of exploration in the quest to understand the complex processes that led to the emergence of life on Earth. By shedding light on the chemistry occurring within water droplets, researchers like Cooks and Qiu breathe new life into the study of life’s chemical evolution. Ultimately, these findings contribute to a more comprehensive understanding of the origins and mechanisms underlying the creation of proteins, the building blocks of all living organisms.
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