Tetrazine-PEG4-Maleimide is a mid-length, sulfhydryl-reactive labeling reagent with enhanced water-solubility provided by a PEG4 spacer.


  • Biocompatible – click reaction occurs efficiently under mild buffer conditions; requires no accessory reagents such as a copper catalyst or reducing agents (e.g. DTT)
  • Chemoselective – tetzines and trans-cyclooctene groups do not react or interfere with other functional groups found in biological samples but conjugate to one another with high efficiency
  • Unprecedented kinetics – inverse-electron demand Diels-Alder chemistry is the fastest bioorthogonal ligation available, delivering conjugates within 30 min at 1 mg/mL concentrations
  • Sulfhydryl-reactive – maleimide reacts rapidly with reduced cysteines and other molecules that contain reduced thiols (–SH groups), attaching TCO moiety via a stable thioether bond
  • Extended PEG4 Spacer – reduces aggregation, minimizes steric hindrance, and enhances solubility
  • Highly stable – tetrazine functional group remains stable in aqueous buffered media (weeks at 4C, pH 7.5)

Tetrazine-PEG4-Maleimide enables simple and efficient incorporation of a tetrazine moiety onto antibodies, cysteine-containing peptides and other thiol-containing molecules. The hydrophilic polyethylene glycol (PEG) spacer arm imparts water-solubility that is transferred to the labeled molecule, thus reducing aggregation of labeled proteins stored in solution. The PEG spacer arm provides a long and flexible connection that minimizes steric hindrance involved with ligation to complementary TCO-containing molecules.

Catalog Number Product DataSheet Size AVAILABILITY Price Qty
Methyltetrazine-PEG4-Maleimide, 10 mg
10 mg In stock
Regular Price:$171.00
On Sale:
Methyltetrazine-PEG4-Maleimide, 25 mg
25mg In stock
Regular Price:$380.00
On Sale:
Methyltetrazine-PEG4-Maleimide, 100 mg
100mg In stock
Regular Price:$932.00
On Sale:

Product Type: Small Molecule
Name: Methyltetrazine-PEG4-Maleimide
Chemical Formula: C24H30N6O7
Molecular Weight: 514.53
Variant MPN: 1068
Format: Red crystalline
Purity: >95%, HPLC
Solubility: DMSO, DMF, MeOH, DCM, THF
Stability: stable 6 months at -20 degC
Storage: -20C. Desiccate
Shipped: Ambient


Applications: Protein-protein conjugation, protein-antibody conjugation, protein-small molecule conjugation, 18F radiolabeling, protein-oligonucleotide conjugation, surface modification

  1. Blackman, M. L., et. al. (2008). "Tetrazine Ligation: Fast Bioconjugation Based on Inverse- Electron-Demand Diels-Alder Reactivity." J. Am. Chem. Soc., 130:13518-13519
  2. Devaraj, N. K., et. al. (2008) "Tetrazine-Based Cycloadditions: Application to Pretargeted Live Cell Imaging." Bioconjugate Chem., 19(12): 2297–2299.
  3. Devaraj, N. K., et. al. (2009) "Fast and Sensitive Pre-Targeted Labeling of Cancer Cells through a Tetrazine/trans-Cyclooctene Cycloaddition." Angew. Chem. Int. Ed., DOI: 10.1002/anie.200903233
  4. Haun, J.B., et. al. (2009) " Probing Intracellular Biomarkers and Mediators of Cell Activation Using Nanosensor and Bioorthogonal Chemistry" ACS Nano., 5:3204-321
  5. Truong NF, Kurt E, Tahmizyan N, Lesher-Pérez SC, Chen M, Darling NJ, Xi W, Segura T. Microporous annealed particle hydrogel stiffness, void space size, and adhesion properties impact cell proliferation, cell spreading, and gene transfer. Acta Biomater. 2019 May 30. pii: S1742-7061(19)30400-3. View Article
  6. Darling NJ, Xi W, Sideris E, et al. Click by Click Microporous Annealed Particle (MAP) Scaffolds. Adv Healthc Mater. 2020;9(10):e1901391. View article

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