MIT News breed · Wetenschap

Peptides Can Form Stable, Functional Structures in Venus-Like Sulfuric Acid Clouds

Scientists have discovered that short peptides can remain stable and fold into specific three-dimensional shapes within highly acidic conditions, similar to those found in the clouds of Venus. This finding challenges previous assumptions about the limits of life and suggests that environments previously considered too harsh may harbor biological potential.

The clouds of Venus, composed of about 98 percent sulfuric acid, were thought to be too acidic for complex biological molecules. However, a new study by MIT researchers demonstrates that short peptides can not only survive but also fold into potentially functional shapes in these extreme conditions. This opens up the possibility of searching for life in planetary environments that do not resemble Earth.

While Venus's surface is inhospitable, its cloud layer, located 30 to 40 miles above the surface, offers milder temperatures. Meteorites containing peptide building blocks regularly enter Venus's atmosphere, raising the question of whether these could form the basis of life if they could withstand the corrosive environment. Previous studies by Seager's lab showed that nucleic acids, lipids, and amino acids could remain intact in highly acidic conditions.

The current research focused on peptides, short chains of amino acids. Using nuclear magnetic resonance (NMR) spectroscopy, the researchers found that peptides remained stable for weeks in nearly pure sulfuric acid. This stability is attributed to the lack of water, which prevents hydrolysis, the process that breaks peptide bonds in acid. Without water, the highly acidic solvent becomes less destructive to peptides.

The study revealed that peptides, when in concentrated sulfuric acid, fold into specific shapes, such as omega loops, which are also found in some naturally occurring proteins. The sulfuric acid molecules appear to act as a scaffold, stabilizing these loop structures. The ability of peptides to form these defined, folded structures in such an acidic environment is a significant finding, suggesting they could potentially perform biological functions.

These findings are considered important and unexpected, raising the prospect that folded protein structures could exist in environments vastly different from Earth. Future research aims to study peptide nucleic acids (PNAs) and longer peptides in concentrated sulfuric acid to further explore the potential for life in extreme conditions.

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