When searching for biosignatures on other worlds, scientists have traditionally focused on planets with Earth‑like liquid surfaces. New evidence shows that the highly acidic clouds of Venus (≈98% H₂SO₄) could also host the building blocks of life. MIT researchers used solution NMR to examine short peptides in nearly pure sulfuric acid and found that they remain stable for weeks and adopt well‑defined three‑dimensional folds.
Because 98% sulfuric acid contains almost no water, acid‑catalyzed hydrolysis of peptide bonds is essentially shut off, allowing the chains to persist. Three peptides—HHQ, HHQ13, and K7—each formed an “omega loop” (a Greek‑letter‑Ω‑shaped motif) in the acid, whereas HHQ forms flat β‑sheets and fibrils in water. The sulfuric‑acid molecules act as a scaffold, slipping into the loop’s centre and locking the conformation.
Omega loops in natural proteins often mediate folding and molecular recognition; their exact function in this context is unknown, but the ability of peptides to stay folded in such a hostile solvent suggests they could perform biological roles in Venus’s cloud layer. The team plans to test other acid‑stable molecules, such as peptide nucleic acid (PNA), and to investigate whether longer peptides adopt similar or new structures in concentrated sulfuric acid.
Funded by the Alfred P. Sloan Foundation, the NOMIS Foundation, and the NIH, this work expands the range of planetary environments considered viable for life.