Biotin-PEG4-STP Ester

Biotin-PEG4-STP Ester (4-Sulfo-2,3,5,6-tetrafluorophenyl ester) is an amine-reactive, water-soluble labeling reagent used to modify proteins, antibodies, and other amine-containing biopolymers in 100% aqueous media. The hydrophilic polyethylene glycol (PEG) spacer arm of this reagent imparts water solubility that is transferred to the labeled molecule, thus reducing aggregation of labeled proteins stored in solution. The PEG spacer arm also gives the reagent a long and flexible connection to minimize steric hindrance involved with binding to avidin molecules.

STP esters undergoes hydrolysis in aqueous media at much slower rate compared to NHS esters allowing for more efficient labeling of biomolecules in aqueous media. Biotin-PEG4-STP Ester reacts readily with primary amines to give the same acylation products as NHS and pentafluorophenyl (PFP) esters.