dPEG®₄-SATA (S-acetyl-dPEG®₄-NHS ester)

dPEG®4-SATA, also known as S-acetyl-dPEG®4-NHS ester, product number 10181, is one of Quanta BioDesign's version of the widely popular thiolation reagent N-succinimidyl-S-acetylthioacetate (SATA). The acetyl-protected thiol is separated from the N-hydroxysuccinimidyl (NHS) ester by a short, amphiphilic, discrete polyethylene glycol (dPEG®) spacer. The dPEG® spacer adds water solubility to the product.

OurdPEG® Technology
Traditional polyethylene glycol (PEG) products are dispersed polymers (Đ > 1). PEG polymers consist of a mixture of different chain lengths and molecular weights of PEG in a Poisson distribution. Quanta BioDesign manufactures PEG products that are not dispersed (Đ = 1). The PEG contained in every PEG product made by Quanta BioDesign has a single molecular weight with a discrete chain length (hence the tradename dPEG®).

Thiolation with dPEG®4-SATA
Thiolation is the process of adding a sulfhydryl group to a molecule. Bioconjugation frequently employs thiolation because the reactions to install thiol groups on molecules or to react molecules with sulfhydryl groups are simple and often chemoselective.

The widely popular SATA reagent thiolates molecules with available amines via the NHS ester. Removal of the acetyl protecting group from the sulfhydryl permits crosslinking between the SATA-modified compound and a target molecule of interest that contains a thiol-reactive group, such as maleimide. Unfortunately, SATA is hydrophobic. Consequently, before use, SATA must be dissolved in a dry, water-miscible organic solvent.

OurdPEG®4-SATA inserts a single molecular weight tetraethylene glycol (dPEG®4) spacer between the protected thiol and the NHS ester. The dPEG® spacer imparts water solubility to the molecule, allowing dPEG®4-SATA to be dissolved and reacted in water without the need for an organic solvent. Also, the dPEG®4 spacer adds hydrodynamic volume to the molecule to which it is conjugated. Increasing the hydrodynamic volume reduces aggregation and precipitation of proteins conjugated to dPEG®4-SATA. Hydroxylamine hydrochloride (CAS number 5470-11-1) easily removes the acetyl protecting group, exposing the sulfhydryl moiety for further reaction.

Any application that can be carried out with a traditional, non-PEGylated SATA reagent can be carried out with our SATA containing a dPEG® spacer. In Bioconjugate Techniques, 3rd edition (see references 1 and 2, below), Greg Hermanson has provided protocols for the thiolation of enzymes, antibodies, avidin, streptavidin, phycobiliproteins, and amine-containing DNA using SATA. All of these protocols can be conducted successfully using dPEG®4-SATA (S-acetyl-dPEG®4-NHS ester) or any of our other SATA reagents.

Application References:

Hermanson, G. T. Chapter 2, Functional Targets for Bioconjugation. Bioconjugate Techniques, 3rd edition. Academic Press: New York, 2013, 127-228, particularly pages 165-170, discussing thiolation and SATA.
Hermanson, G. T. Chapter 18, PEGylation and Synthetic Polymer Modification. Bioconjugate Techniques, 3rd edition. Academic Press: New York, 2013, 787-838.

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