Thiol-PEG3-amine

Thiols and amines are widely used handles for modular PROTAC assembly, enabling efficient conjugation of ligands and controlled linker architecture. Thiol-PEG3-amine provides a PEG-based, flexible spacer that can improve solubility and reduce steric constraints between binding modules. Its functional groups support orthogonal coupling strategies commonly employed in targeted protein degradation workflows, and the detailed structural and synthetic considerations are provided below.

Structure: Thiol-PEG3-amine is a polyethylene glycol linker bearing a terminal thiol and a primary amine. The molecule contains ether linkages within the PEG chain and terminal heteroatom functionalities, enabling hydrogen bonding and strong solvation. Its flexible, hydrophilic backbone supports conformational adaptability in conjugates.

Reactivity: The terminal thiol is typically used for thio-Michael/thiol–maleimide or disulfide-exchange style conjugations, while the primary amine supports amide bond formation via activated carboxylic acids or NHS/ester intermediates. Linker coupling is commonly performed under mild, aqueous or mixed solvent conditions, with pH control to preserve thiol reactivity and minimize side reactions. Orthogonal protection of the thiol is often used to enable sequential assembly steps.