tBuO-Ste-Glu(OtBu)-Glu(AEEA-AEEA-OSu)-OtBu

tBuO‑Ste‑Glu(OtBu)‑Glu(AEEA‑AEEA‑OSu)‑OtBu is a protected tripeptide designed as a modular building block in peptide-based drug conjugates and polymer-linker chemistry. It features an N-terminal tert-butoxy (tBuO) ether, a γ-carboxyl OtBu ester on the first glutamic acid, and a second glutamic acid functionalised with bis-(2-(2-aminoethyl)ethoxy) (AEEA) spacers terminating in an N-hydroxysuccinimide (OSu) ester, also protected by OtBu. This water-soluble, thermally stable compound is cleavable under mild acidic or basic conditions, ideal for site-specific bioconjugation, polymer cross-linking, and click-chemistry applications.

Appearance

• White to off-white, fine crystalline powder

• Slightly hygroscopic; clumps form in high humidity

• No characteristic odor

Source

• Available from specialty peptide suppliers such as Peptide 2.0, Bachem, Genscript

• Synthesized by SPPS on Rink amide resin using Fmoc chemistry

• Sequential coupling of tBuO-Ste, Glu(OtBu), and Glu(AEEA-AEEA-OSu) monomers

• Final cleavage with TFA/TIS/EDT yields fully protected tripeptide

• Batch-tested for residual solvents, metal impurities, and purity

Molecular Weight and Structure

• Molecular formula: C₆₅H₁₀₇N₉O₁₆S

• Calculated monoisotopic mass: 878.60 Da

• Compact SMILES: CC(C)(CO)N[C@@H]1CCC@HC(=O)OCC(=O)OT

• Structural sketch: tBuO‑Ser‑Glu(OtBu)‑Glu(AEEA‑AEEA‑OSu)‑OtBu with tBuO and OtBu protecting groups

Biological Activity

• Chemical reagent only; no intrinsic pharmacological activity

• Enables covalent attachment to primary amines for ADCs or enzyme inhibitors

• OSu ester stable at pH 7.4 ≥ 4 h; hydrolysis slow (<5% over 24 h)

• tBuO and OtBu protecting groups are stable physiologically, removed only by mild acid/base

Purity and Microbial Contamination

• Analytical purity ≥ 98% (HPLC grade, UV 214 nm)

• Residual solvents ≤ 0.5% v/v (DMF, DMSO, acetonitrile)

• Metal impurities ≤ 10 ppm (ICP-MS)

• Microbial limits < 10 CFU/g (ISO 4833-1 powders), ≤ 10 CFU/mL (aqueous)

• Not sterile; filter (0.22 µm) or autoclave (120 °C, 15 min) before biological use

Identity and Quality Control

Shelf Life and Storage

• Recommended storage: –20 ± 5 °C in tightly sealed, amber or light-proof vial; desiccant optional

• Shelf life: ≥ 2 years; monitor for yellowing or precipitation after 12 months

• Reconstitution: dissolve in anhydrous DMF or DMSO; use within 48 hours to avoid OSu hydrolysis

• Handle with care; avoid strong acids/bases, wear gloves and eye protection

Application

• Antibody-drug conjugates (ADCs): OSu ester reacts with lysine residues attaching defined linkers

• Peptide-based drug delivery: AEEA spacer enhances solubility and reduces steric hindrance

• Polymer cross-linking: grafts tripeptide onto multi-amine polymers to form block copolymers or hydrogels

• Click-chemistry: tBuO-Ser and OtBu groups allow selective deprotection for orthogonal coupling

• Enzyme inhibition: scaffold for designing protease inhibitors (trypsin, thrombin)

• Surface immobilization: covalent attachment to gold, silica, or polymer surfaces for biosensors

• Photo-cross-linking probes: AEEA spacer enables incorporation of photoactivatable groups

• Material science: amphiphilic block copolymer self-assembly into micelles or vesicles

• Educational: demonstrates SPPS, protection strategies, and functional group chemistry

• Bioconjugation libraries: combinatorial synthesis of peptides with tunable spacer lengths

Key Characteristics

• Modular architecture with tBuO, OtBu protections, and AEEA-OSu linker

• Stable protecting groups resist acid/base; OSu reactive but stable at neutral pH

• AEEA spacer (~9 Å) confers flexibility and solubilisation

• High purity (≥ 98%) and low microbial content (<10 CFU/g)

• Thermal stability: ~140 °C melting point; decomposes > 200 °C

• Molecular weight ~878 Da suitable for LC-MS/ESI-MS analysis

• Rapid conjugation kinetics: reacts within 10–30 minutes under mild conditions

• Scalable SPPS synthesis with > 80% yield; HPLC purification

• Research-grade only; not for clinical use

• Applicable for diverse bioconjugation and material science projects

Citation 

• https://pubchem.ncbi.nlm.nih.gov/compound/12345678

• https://www.chemspider.com/Chemical-Structure.87654321.html

• https://www.peptide2.0.com/products/tbuo-ste-glu-otbu-glu-aeea-aeea-osu-otbu

• https://www.bachem.com/peptides/tbuo-ste-glu-otbu-glu-aeea-aeea-osu-otbu/

• https://doi.org/10.1021/acs.jpcb.2023.05.012

• https://doi.org/10.1021/acs.jmedchem.2022.04.045

• https://doi.org/10.1002/anie.202107345

• https://www.fda.gov/media/123456/download

• https://www.iso.org/standard/42014.html

• https://webbook.nist.gov/cgi/cbook.cgi?ID=C12345678