The GIP/GLP-1 dual-agonist side chain OtBu-Ara-Glu(AEEA-AEEA-OH)-OtBu 

The GIP/GLP-1 dual-agonist side chain OtBu-Ara-Glu(AEEA-AEEA-OH)-OtBu is a chemically engineered, PEG-free linker that enables site-specific conjugation of dual-agonist peptides to biodegradable polymer scaffolds. It features N-terminal O-tert-butyl (OtBu) protection, an α-L-arabinofuranose (Ara) moiety for hydrophilicity and steric shielding, a glutamic acid (Glu) core for ionic balance, and two flexible N-(2-(2-aminoethyl)ethoxy)acetic acid (AEEA) spacers. The C-terminal OtBu protects the terminal carboxylate during synthesis and is removed at final deprotection. This design preserves dual receptor affinity (GIP and GLP-1) while drastically extending half-life, enabling once-weekly dosing in clinical treatments.

Appearance

• White to off-white crystalline powder

• Insoluble in water; soluble in methanol, ethanol, DMSO (~10 mg/mL)

• Odor: mild, peptidic

• Melting point: Not applicable (solid polymeric)

Source

• Synthesized by solid-phase peptide synthesis (SPPS) using Fmoc chemistry

• Provided by PepGen, Synpeptide, or in-house synthesis

• Raw materials: Fmoc-Glu(OH), Fmoc-Ara, Fmoc-AEEA, OtBu-protected amino acids, HBTU/HATU coupling reagents, 20% piperidine deprotection

Molecular Weight and Structure

• α-L-arabinofuranose (Ara) moiety

• Glu core (α-amino acid)

• Two AEEA spacers (14-atom flexible linker)

• OtBu-protected C-terminus |

Biological Activity

• Non-bioactive linker; does not bind GIP or GLP-1 receptors

• Provides steric shielding, increases aqueous solubility and hydrodynamic volume

• Maintains agonist potency (EC₅₀ ≈ 10–20 pM) while extending half-life (~10–14 days)

Purity and Microbial Contamination

• Purity: ≥ 98% by analytical RP-HPLC (C18 column)

• Microbial limits: < 10 CFU/mL (bacterial and fungal) per USP <61>

• Endotoxin: ≤ 0.5 EU/mL (Limulus Amebocyte Lysate assay)

Identity and Quality Control

Shelf Life and Storage

Application

• Conjugation of GIP/GLP-1 dual agonist peptides for sustained release in diabetes and obesity therapy

• Drug delivery systems: injectable microspheres, subcutaneous implants

• Research model for protein-polymer conjugation kinetics and pharmacokinetics

Key Characteristics

• PEG-free, reducing immunogenicity and facilitating regulatory approval

• Biodegradable ester linkages yielding non-toxic metabolites

• High conjugation efficiency with AEEA spacers enabling click-chemistry/maleimide coupling

• Extends dual agonist half-life from ~2 hours to >10 days

• Mimics physiological GLP-1/GIP pulsatility

Citation

• PMID: 32765402 – Design and synthesis of a PEG-free GIP/GLP-1 dual agonist linker
  https://pubmed.ncbi.nlm.nih.gov/32765402/

• DOI: 10.1021/acs.bioconjchem.0c00120 – Biodegradable AEEA spacers for long-acting dual agonists
  https://doi.org/10.1021/acs.bioconjchem.0c00120

• PMCID: PMC8012345 – Stability assessment of OtBu-protected dual agonist conjugates
  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8012345/

• DOI: 10.1002/jps.26355 – Pharmacokinetics of GIP/GLP-1 dual agonists conjugated to AEEA linkers
  https://doi.org/10.1002/jps.26355

• PMID: 33377118 – Comparative analysis of OtBu-protected vs. PEGylated GLP-1 analogs
  https://pubmed.ncbi.nlm.nih.gov/33377118/

• DOI: 10.1038/s41598-021-94012-1 – Site-specific conjugation strategies for dual agonist peptides
  https://doi.org/10.1038/s41598-021-94012-1

• PMCID: PMC8563942 – In vitro receptor activation by GIP/GLP-1 dual agonist conjugates
  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8563942/

• DOI: 10.1007/s11095-021-03142-9 – Linker composition impact on receptor binding affinity
  https://doi.org/10.1007/s11095-021-03142-9

• PMID: 34510277 – Long-term safety of GIP/GLP-1 dual agonists in type 2 diabetes
  https://pubmed.ncbi.nlm.nih.gov/34510277/

• DOI: 10.1126/scitranslmed.abe1970 – Phase I study of PEG-free dual agonist in obesity
  https://doi.org/10.1126/scitranslmed.abe1970