Peptides adopt stable omega-loop structures in concentrated sulfuric acid.

Authors

Jia Yi Zhang, Aurelio J Dregni, Janusz J Petkowski, Sara Seager, Mei Hong

Published in

Proceedings of the National Academy of Sciences of the United States of America. Volume 123. Issue 37. Pages e2618039123. Sep 15, 2026. Epub Sep 04, 2026.

Abstract

The search for life beyond Earth has focused on planets and moons with liquid water, reflecting the assumption that complex biomolecules require aqueous environments to remain stable and functional. Such a view excludes a wide class of planetary settings, including the concentrated sulfuric acid clouds of Venus, where extreme acidity and minimal water are thought to preclude molecular structure despite suitable temperatures. A growing body of evidence shows that a wide range of organic molecules can remain stable in concentrated sulfuric acid, including nucleic acid bases, amino acids, lipid micelles and vesicles, and peptide nucleic acid (PNA), but such stability does not address whether macromolecules can retain folded structures required for function. Using NMR spectroscopy, here we show that three peptides adopt stable, well-defined folded structures in concentrated (98% w/w) sulfuric acid, an extreme solvent environment that has been long assumed to be incompatible with biomolecules. The peptides form compact Ω-loop conformations stabilized by solvent-mediated interactions and intramolecular hydrogen bonding. This finding strongly counters conventional thinking where sulfuric acid would destroy peptide bonds via acid-catalyzed hydrolysis. Here, the near absence of water in 98% (w/w) sulfuric acid means hydrolysis does not occur. The result identifies a regime in which macromolecular structure persists under conditions long considered incompatible with life. The finding expands the range of planetary environments that may support complex chemistry and motivates renewed consideration of chemically diverse exoplanets in the search for signs of life beyond Earth.

PMID:
42696554
Bibliographic data and abstract were imported from PubMed on 05 Sep 2026.

Read full publication at:
Please sign in to see all details.

Stats

1-terrible, 9-excellent. How would you rate this publication? Sign in in to submit your rating.

Post a comment

You need to be signed in to post comments. You can sign in here.

Comments

There are no comments yet.