Tr-PEG5-OH

Tr-PEG5-OH is a polyethylene glycol-based PROTAC linker building block designed to connect ligands while tuning solubility, flexibility, and effective spatial positioning in targeted protein degradation constructs. Its hydrophilic PEG segment can help reduce aggregation and improve handling in common coupling workflows. The molecule is described in detail below, including its structural characteristics and the practical considerations for PROTAC assembly.

Structure: Tr-PEG5-OH is a PEG-derived linker bearing a terminal hydroxyl group, enabling covalent attachment to complementary PROTAC fragments. It contains repeating ether linkages that confer conformational flexibility and strong hydrogen-bonding capacity, supporting favorable aqueous solubility and stable, non-covalent interactions during linker transit.

Reactivity: The terminal hydroxyl group is typically used for derivatization into activated intermediates (for example, via esterification or ether formation) prior to final conjugation to ligand scaffolds. PROTAC coupling commonly employs standard amide/ester-forming chemistries under inert or controlled conditions, using coupling reagents and base in polar organic solvents; reaction efficiency depends on activation state, steric accessibility, and solvent compatibility with PEG chains.