TCO-PEG3-amine

TCO-PEG3-amine is a functionalized polyethylene glycol linker designed for building PROTACs and related targeted degradation constructs. Its PEG-based spacer improves linker flexibility and solubility, helping to tune the effective geometry between a targeting ligand and an E3-recruiting moiety. The TCO handle enables bioorthogonal conjugation strategies that are widely used to generate stable, well-defined PROTAC architectures. The following sections describe the structure and practical reactivity considerations in detail below.

Structure: TCO-PEG3-amine contains a trans-cyclooctene (TCO) reactive olefin conjugated to a PEG spacer terminating in a primary amine. The molecule features an ether-rich PEG chain, a carbon–carbon double bond within the TCO motif, and a terminal amine for downstream coupling. These features support hydrophilicity, conformational flexibility, and versatile conjugation chemistry.

Reactivity: The TCO group participates in strain-promoted cycloaddition with tetrazines under mild, aqueous-compatible conditions, enabling rapid formation of a stable conjugate via an inverse-electron-demand Diels–Alder mechanism. The terminal amine supports amide or urea formation through standard coupling chemistries, typically using activated carboxylic acid derivatives and base in common organic solvents. Reaction design should prioritize compatibility with the tetrazine and the stability of the conjugated partners.