MIT study finds life’s building blocks can survive Venus’s acid clouds

Peptides can not only survive but fold into biologically useful shapes in the sulfuric acid clouds that blanket Venus, according to new research from MIT, challenging long-held assumptions about where life might take root beyond Earth.

The study, published this week in the Proceedings of the National Academy of Sciences, found that short chains of amino acids remained stable for weeks in solutions of nearly pure sulfuric acid and adopted three-dimensional structures known as omega loops — formations occasionally found in naturally occurring proteins on Earth.thedebrief+1

Building Blocks That Endure

The Venus cloud layer, stretching 30 to 40 miles above the planet's scorching surface, features temperatures mild enough to theoretically support life. But the clouds are composed of roughly 98 percent sulfuric acid, a substance strong enough to dissolve metals and lethal to all known terrestrial organisms.news.mit

The research, led by graduate student Jia Yi Zhang with senior authors Mei Hong, Sara Seager, and Janusz Petkowski, builds on a series of MIT studies begun in 2020 that progressively tested whether biological molecules could withstand such conditions. Earlier work showed that nucleic acid bases, lipids, and amino acids all maintained their integrity in concentrated sulfuric acid. The new paper extends those findings to peptides, which are more complex structures essential to biological function.physics.mit+2

Counterintuitively, the near-total absence of water at 98 percent acid concentration may explain the peptides' resilience. Hydrolysis — the reaction that normally breaks peptide bonds in acidic conditions — requires water molecules that are scarce in such concentrated solutions.news.mit

"Without water, an acid that you would consider a harsh solvent suddenly is not as menacing as one might think," Hong said.news.mit

Unexpected Structures

Using an 800-megahertz nuclear magnetic resonance spectrometer, the team found that sulfuric acid molecules acted as scaffolds, sliding into the center of peptide loops and holding them in omega-loop conformations that would not typically form in water. Such structures are thought to play roles in protein folding and molecular recognition in terrestrial biology.news.mit

Adriaan Bax, chief of the Section on Biophysical NMR at the National Institutes of Health, called the results "important and unexpected," noting they raise the prospect that folded protein structures could exist in environments radically different from Earth's.news.mit

Widening the Search

The findings arrive as private missions to Venus gain momentum. Seager, who is leading the Morning Star Missions to Venus, said the work should prompt a broader view of habitability in the search for exoplanets. Follow-up research will investigate whether double-stranded peptide nucleic acid — a synthetic analog of DNA — can replicate DNA's structure under these conditions.thedebrief+1

"We're seeking exoplanets that might be a true Earth twin, but what if they're all Venuses?" Seager said. "Our findings definitely open up a whole range of possibilities."news.mit