DBCO-NHCO-PEG3-acid

This DBCO-NHCO-PEG3-acid linker is designed for efficient incorporation into PROTAC constructs via bioorthogonal click chemistry. Its DBCO handle enables selective conjugation to azide-containing ligands under mild conditions, while the PEG-based spacer promotes favorable solubility and reduces steric constraints that can impair ternary complex formation. The acid functionality supports straightforward coupling to targeting moieties, and the overall architecture is well suited for systematic linker-length and chemistry optimization. Detailed structural and reactivity guidance is provided below.

Structure: The molecule contains a cyclooctyne (DBCO) core for strain-promoted azide–alkyne cycloaddition, connected through a carbamate/amide linkage and a polyethylene glycol (PEG) spacer. An acid terminus provides a polar, ionizable group, supporting aqueous compatibility and chemical handle availability for PROTAC assembly.

Reactivity: PROTAC construction using this linker commonly relies on strain-promoted azide–alkyne cycloaddition with azide-bearing partners, typically performed in aqueous buffer or mixed solvent systems at mild temperature to preserve sensitive ligands. The reaction proceeds via a concerted cycloaddition mechanism without the need for copper catalysis. For coupling to targeting ligands, the acid group is suitable for amide-bond formation using standard activating chemistries under controlled pH, followed by purification to remove residual reagents.