29CK | pdb_000029ck

SOLUTION STRUCTURE OF GLUCAGON PEPTIDE AT pH 2.5

• PDB DOI: https://doi.org/10.2210/pdb29CK/pdb

• Classification: HORMONE
• Organism(s): Homo sapiens
• Mutation(s): No 


• Deposited: 2026-03-05 Released: 2026-08-12 
• Deposition Author(s): Santoro, A., Buonocore, M., D'Ursi, A.M.
• Funding Organization(s): Not funded

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Experimental Data Snapshot

• Method: SOLUTION NMR
• Conformers Calculated: 100 
• Conformers Submitted: 7 
• Selection Criteria: target function 

Literature

Conformational determinants of glucagon stability and aggregation kinetics in aqueous and commercial formulations.

Santoro, A., Macis, M., Buonocore, M., Ricci, A., D'Ursi, A.M.

(2026) Protein Sci 35: e70750-e70750

• PubMed: 42557738 
• DOI: https://doi.org/10.1002/pro.70750
• Primary Citation Related Structures: 
  28TG, 28UX, 29CK


• PubMed Abstract: 
  

  Glucagon is a well-established therapeutic peptide, widely used to treat hypoglycemia. Like many peptide drugs, it offers advantages such as specificity, biocompatibility, and high affinity for receptor targets, but suffers from limited physical and chemical stability. In particular, improper conditions can promote the formation of amyloid fibrils, leading to loss of biological activity and, in some cases, cytotoxicity. Understanding the conditions that modulate the structural behavior of glucagon is therefore crucial. Currently, two injectable formulations are available on the market: a lyophilized vial of glucagon with lactose at acidic pH, and a more recent auto-injector ready-to-use (RTU) formulation containing glucagon in dimethyl sulfoxide (DMSO) with trehalose. In this study, we investigated the conformational properties of glucagon in these two marketed formulations and compared them with glucagon dissolved in aqueous solution at pH 3.5, a metastable condition prone to aggregation. Preliminary circular dichroism and fluorescence spectroscopy were used to confirm glucagon stability over time; subsequently, NMR analysis showed that structural destabilization consistently begins at the C-terminal region, while the ¹¹ Ser-Leu ¹⁴ segment remains structured across all environments. These findings highlight two key determinants of glucagon stability and aggregation. Strategies that preserve the integrity of the C-terminal region while stabilizing the ¹¹ Ser-Leu ¹⁴ motif may improve peptide solubility and extend shelf life, providing a rational basis for the design of next-generation glucagon formulations for emergency use.

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Organizational Affiliation: 
• Department of Pharmacy, University of Salerno, Salerno, Italy.
Fresenius Kabi iPSUM, Rovigo, Italy.
Department of Chemical Sciences, University of Naples "Federico II," Complesso Universitario Monte Sant'Angelo, Naples, Italy.

Biological Assembly 1  

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Monomer - A1 

Biological assembly 1 assigned by authors and generated by (software)

Biological Assembly Evidence: NMR Distance Restraints

Macromolecule Content 

• Total Structure Weight: 3.49 kDa 
• Atom Count: 245 
• Modeled Residue Count: 29 
• Deposited Residue Count: 29 
• Unique protein chains: 1

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Pro-glucagon	A	29	Homo sapiens	Mutation(s): 0
UniProt & NIH Common Fund Data Resources
Find proteins for P01275 (Homo sapiens) Explore P01275  Go to UniProtKB:  P01275
GTEx:  ENSG00000115263

Experimental Data & Validation

Experimental Data

• Method: SOLUTION NMR
• Conformers Calculated: 100 
• Conformers Submitted: 7 
• Selection Criteria: target function 

Structure Validation

Entry History 

& Funding Information

Deposition Data

• Released Date: 2026-08-12 
Deposition Author(s): Santoro, A., Buonocore, M., D'Ursi, A.M.

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Funding Organization	Location	Grant Number
Not funded		--

Revision History  

• Version 1.0: 2026-08-12
  Type: Initial release
  
• Version 1.1: 2026-08-19
  Changes: Database references