All-D Amino Acid Stapled Peptides Enter Cells While Resisting Every Known Enzyme
First all-D stapled peptides achieved cellular activity against the p53-Mdm2 cancer target with complete proteolytic stability — combining two complementary drug design strategies.
Quick Facts
What This Study Found
The team started with a known all-D linear peptide that potently inhibits the p53-Mdm2 interaction in a test tube but cannot enter cells. Using computational modeling, they designed optimal staple placement to create macrocyclic versions.
The resulting stapled and stitched all-D peptides showed increased alpha-helical structure, improved binding to the Mdm2 target, complete resistance to proteolytic enzymes, and, most importantly, cellular activity.
This represents the first demonstration that combining D-amino acids with hydrocarbon stapling can produce peptides that are both enzyme-proof and cell-permeable, overcoming two of the biggest barriers to peptide drug development.
Key Numbers
First all-D stapled peptides with cellular activity; complete proteolytic stability; improved helicity and binding
How They Did This
This was a laboratory study combining computational modeling and peptide chemistry. Researchers used molecular modeling to predict optimal staple positions on an all-D peptide scaffold. They synthesized stapled and stitched variants and tested them for helicity (circular dichroism), target binding, proteolytic stability, and cellular activity against the p53-Mdm2 interaction.
Why This Research Matters
Peptide drugs face two main problems: enzymes break them down, and they cannot get into cells. D-amino acids solve the first problem but not the second. Stapling solves the second but not always the first. Combining both strategies simultaneously could open the door to a new class of highly stable, cell-permeable peptide therapeutics.
The p53-Mdm2 interaction is one of the most important targets in cancer research, and blocking it could reactivate the body's natural tumor suppressor.
The Bigger Picture
Peptide drugs face two fundamental challenges: enzyme degradation and cell membrane penetration. Combining D-amino acids and stapling addresses both simultaneously, creating a platform for developing peptide drugs that are stable in the body and can reach intracellular targets.
What This Study Doesn't Tell Us
This is an early proof-of-concept study. The cellular activity was demonstrated but detailed potency data, selectivity profiling, and in vivo testing were not reported.
Whether this combined strategy works for targets beyond p53-Mdm2 remains to be seen.
Questions This Raises
- ?Does the combined strategy work for peptide targets beyond p53-Mdm2?
- ?What is the in vivo pharmacokinetics of all-D stapled peptides?
- ?Can these be manufactured at scale for clinical development?
Trust & Context
- Key Stat:
- Two barriers solved all-D amino acids provide complete enzyme resistance while stapling enables cell penetration — first combination achieving both
- Evidence Grade:
- Preliminary evidence from proof-of-concept cell-based studies. Cellular activity demonstrated but detailed potency and in vivo data not reported.
- Study Age:
- Published in 2020. The dual D-amino acid + stapling strategy continues to be developed.
- Original Title:
- Macrocyclization of an all-d linear α-helical peptide imparts cellular permeability.
- Published In:
- Chemical science, 11(21), 5577-5591 (2020)
- Authors:
- Kannan, Srinivasaraghavan(3), Aronica, Pietro G A(2), Ng, Simon, Gek Lian, Dawn Thean, Frosi, Yuri, Chee, Sharon, Shimin, Jiang, Yuen, Tsz Ying, Sadruddin, Ahmad, Kaan, Hung Yi Kristal, Chandramohan, Arun, Wong, Jin Huei, Tan, Yaw Sing, Chang, Zi Wei, Ferrer-Gago, Fernando J, Arumugam, Prakash, Han, Yi, Chen, Shiying, Rénia, Laurent, Brown, Christopher J, Johannes, Charles W, Henry, Brian, Lane, David P, Sawyer, Tomi K, Verma, Chandra S, Partridge, Anthony W
- Database ID:
- RPEP-04895
Evidence Hierarchy
Frequently Asked Questions
Why use D-amino acids in drugs?
Normal (L) amino acids are recognized and destroyed by enzymes in the body. D-amino acids are mirror images that enzymes cannot break down, making the drug last much longer.
What does stapling add?
Stapling locks the peptide into a helical shape that can cross cell membranes. Without stapling, peptides bounce off cells and cannot reach their intracellular targets. Together, D-amino acids + stapling = stable + cell-penetrating.
Read More on RethinkPeptides
Cite This Study
https://rethinkpeptides.com/research/RPEP-04895APA
Kannan, Srinivasaraghavan; Aronica, Pietro G A; Ng, Simon; Gek Lian, Dawn Thean; Frosi, Yuri; Chee, Sharon; Shimin, Jiang; Yuen, Tsz Ying; Sadruddin, Ahmad; Kaan, Hung Yi Kristal; Chandramohan, Arun; Wong, Jin Huei; Tan, Yaw Sing; Chang, Zi Wei; Ferrer-Gago, Fernando J; Arumugam, Prakash; Han, Yi; Chen, Shiying; Rénia, Laurent; Brown, Christopher J; Johannes, Charles W; Henry, Brian; Lane, David P; Sawyer, Tomi K; Verma, Chandra S; Partridge, Anthony W. (2020). Macrocyclization of an all-d linear α-helical peptide imparts cellular permeability.. Chemical science, 11(21), 5577-5591. https://doi.org/10.1039/c9sc06383h
MLA
Kannan, Srinivasaraghavan, et al. "Macrocyclization of an all-d linear α-helical peptide imparts cellular permeability.." Chemical science, 2020. https://doi.org/10.1039/c9sc06383h
RethinkPeptides
RethinkPeptides Research Database. "Macrocyclization of an all-d linear α-helical peptide impart..." RPEP-04895. Retrieved from https://rethinkpeptides.com/research/kannan-2020-macrocyclization-of-an-alld
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkPeptides research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.