endo-BCN-PEG8-NHS ester is a monodisperse PEG linker containing an NHS ester group and a BCN group. It can be used to label the primary amines (-NH2) of proteins, amine-modified oligonucleotides, and other amine-containing molecules. The BCN group can react with azide-tagged biomolecules under copper free condition. The hydrophilic PEG spacer increases solubility in aqueous media.
To a solution of H2N-PEG8-COOH (822 mg, 1.86 mmol) in THF:H20 1 : 1 (20 mL) were added BCN-OSu (23) (651 mg, 2.23 mmol) and Et3N (774 μ, 5.59 mmol). The reaction was stirred at r.t. for 1.5 h andd acidified to pH 1 followed by extraction with EtOAc (3 x 35 mL). The combined organic layers were dried over Na2S04, filtered and the solvent removed under reduced pressure. The crude product was then dissolved in dry DCM (20 mL) and subsequently DCC (461 mg, 2.23 mmol) and NHS (257 mg, 2.23 mmol) were added. After stirring at r.t. for 1 h, the reaction was filtered and the filtrate concentrated in vacuo. Flash chromatography (MeCN, MeCN:H20 30: 1) afforded BCN-PEG8-COOSu.
PROTACs contain two different ligands connected by a linker; one is a ligand for an E3 ubiquitin ligase and the other is for the target protein. PROTACs exploit the intracellular ubiquitin-proteasome system to selectively degrade target proteins.
structure and hydrogen bonding
endo-BCN-PEG8-NHS ester contains an NHS ester group and a BCN group on its ends. While the BCN group readily react with azide-tagged biomolecules, the NHS ester can be utilized for conjugation with amines bearing proteins, oligonucleotides, and other molecules. The hydrophilic PEG spacer increases the aqueous solubility of the resulting biomolecules.
