Mapping Cis-Proline Conformations in 150 Cyanobacterial Cyclic Peptides | Research

The takeaway

51 of 150 cyanobacterial cyclic peptides contained cis-prolyl amide bonds, a conformation affecting biological activity that is often under-reported in the literature.

34% have cis-Pro
Over a third of cyanobacterial cyclic peptides contain cis-proline conformations, a feature often unreported but functionally significant

What the researchers found

51 out of 150 cyanobacterial cyclic peptides contained cis-prolyl amide bonds, a functionally significant conformation that is frequently unreported in the literature.

Why it matters

Proline cis/trans isomerism affects peptide function and drug-target binding. Under-reporting this information hinders rational design of peptide-based drugs from cyanobacterial natural products.

How the study worked

Manual review of chemical structures and NMR chemical shifts of 150 cyanobacterial cyclic peptides containing proline residues, focusing on cis/trans isomerism.

What this study cannot tell us

Manual review may miss some compounds. Functional consequences of cis-Pro not always experimentally validated. NMR data quality varies across publications.

How to read the evidence

Systematic manual literature review with NMR analysis. Comprehensive structural cataloging resource.

When this study was published

Published in 2025.

The bigger picture

Accurate structural characterization of natural product peptides, including proline conformation, is essential for translating nature's chemistry into new drugs.

Questions still open

Does cis-Pro conformation consistently enhance or reduce bioactivity?
Can synthetic methods control cis/trans-Pro in cyclic peptide production?
Should all future cyclic peptide publications report proline conformation explicitly?

Common questions

What is cis-proline and why does it matter?

Proline is an amino acid that can adopt two shapes (cis or trans). In cyclic peptides from cyanobacteria, the shape affects how the peptide binds to targets. Knowing the correct shape is essential for drug design.

Why are cyanobacterial peptides important?

Cyanobacteria (blue-green algae) produce thousands of cyclic peptides with antiparasitic, antimicrobial, and anticancer activities. Understanding their structures enables development of new drugs from these natural products.

Read the original research

Cyanobacterial Cyclic Peptides Containing cis-Pro Conformation.

Chemistry (Weinheim an der Bergstrasse, Germany), e02932

View on PubMed ↗Publisher’s paper ↗

Citation

Haedar, Jabal Rahmat; Khan, Abujunaid Habib; Coxon, Christopher R; Phan, Chin-Soon. (2026). Cyanobacterial Cyclic Peptides Containing cis-Pro Conformation.. Chemistry (Weinheim an der Bergstrasse, Germany), e02932. https://doi.org/10.1002/chem.202502932