C20-OtBu-Glu(OtBu)-AEEA-AEEA-OH

Why is this molecule so important?

In the design of long‑acting peptide drugs such as Tirzepatide (Mounjaro®/Zepbound®) and Semaglutide (Ozempic®/Rybelsus®), the fatty acid side chain binds reversibly to human serum albumin (HSA) to extend plasma half‑life. C20-OtBu-Glu(OtBu)-AEEA-AEEA-OH is a key building block that incorporates this fatty acid chain. The PEG2‑based AEEA‑AEEA spacer of C20-OtBu-Glu(OtBu)-AEEA-AEEA-OH provides a hydrophilic, flexible linker that improves solubility and reduces aggregation, while the glutamic acid core acts as a branching point orienting the C20 chain away from the peptide backbone. The tert‑butyl protecting groups (OtBu) on C20-OtBu-Glu(OtBu)-AEEA-AEEA-OH are removed during the final deprotection step of SPPS, exposing the free diacid for albumin binding. The free carboxylic acid at the terminus of the AEEA‑AEEA segment in C20-OtBu-Glu(OtBu)-AEEA-AEEA-OH serves as the attachment point to the peptide chain, typically conjugated to a lysine ε‑amine near the C‑terminus. Thus, C20-OtBu-Glu(OtBu)-AEEA-AEEA-OH is indispensable for once‑weekly peptide therapeutics.

Product Parameters

Key Applications

1. Synthesis of Tirzepatide (GLP‑1/GIP Dual Agonist)

Tirzepatide is a 39‑amino‑acid peptide that acts as a dual agonist of the glucose‑dependent insulinotropic polypeptide receptor (GIPR) and the glucagon‑like peptide‑1 receptor (GLP‑1R). It is approved for the treatment of type 2 diabetes and obesity. The C20 side chain is attached to the ε‑amine of a lysine residue at position 20 (or through a short spacer) via standard amide bond formation. During the final TFA cleavage and deprotection step, the two OtBu groups are removed, exposing the free C20 diacid that binds to human serum albumin. This albumin binding reduces renal clearance, giving Tirzepatide its characteristic once‑weekly dosing profile.

2. Development of Other Albumin‑Binding Peptide Therapeutics

The structural design of this side chain — C20 fatty diacid + glutamate branch point + AEEA‑AEEA hydrophilic spacer + terminal carboxylic acid — represents a modular platform that can be applied to other GLP‑1 analogs, amylin analogs, and other peptide drugs requiring half‑life extension. The C20 chain length has been optimized for tight but reversible albumin binding; shorter chains (C18, as in Semaglutide) provide slightly faster dissociation and different pharmacokinetics. Researchers can use this building block to synthesize side chain‑modified peptide libraries for structure‑activity relationship studies.

3. Icodec Side Chain Variants

This compound is also used as the side chain for Icodec, a once‑weekly basal insulin analog. The same C20‑Glu‑AEEA‑AEEA architecture attaches to the insulin peptide chain via the terminal carboxylic acid, enabling albumin‑bound circulation and sustained glucose‑lowering activity.

4. Semaglutide Impurity Identification

This compound is also characterized as a process‑related peptide impurity in Semaglutide manufacturing, with distinct chromatographic retention and mass spectral signatures that are useful for HPLC and LC‑MS method development and quality control.

Quality Assurance at Cosperpharm

● HPLC purity (≥98.0%, UV detection at 210 nm or ELSD/CAD for PEG detection)

● LC‑MS for molecular weight confirmation (expected [M+H]⁺ = 875.2)

● ¹H NMR and ¹³C NMR for full structure confirmation

● Karl Fischer water content (≤0.5%)

● Residual solvents by GC (DMF, DCM, ethyl acetate, acetonitrile)

● Appearance (white to off‑white solid)

● Microbial limits (USP‑compliant upon request)

A comprehensive COA, MSDS, origin certificate, and stability summary accompany every shipment. Accelerated stability data (25 °C/60% RH for 6 months) and long‑term stability data (24 months at –20 °C) are available upon request. A Drug Master File (DMF) can be filed with regulatory agencies after signing a Confidential Disclosure Agreement.

Contact us

Need CAS 1188328‑37‑1 for your Tirzepatide or other albumin‑binding peptide? Reach out to Cosperpharm. Samples, bulk pricing, and custom packaging are just an email away. Let’s get your synthesis moving.