Bis-dPEG®₃-biotin

Bis-dPEG®3-biotin, product number 10325, is an exceptional offering from Quanta BioDesign, Ltd. Because it is composed of a dPEG®3 spacer with biotin attached to each end of the spacer, Bis-dPEG®3-biotin offers customers unique opportunities for exploiting the biotin-avidin/streptavidin affinity.


The affinities between biotin-avidin and biotin-streptavidin are the strongest non-covalent bonds presently known to science. Though they have different amino acid sequences, the structures of these two proteins are similar. Avidin and streptavidin are tetrameric proteins. As such, they tightly bind up to four biotins per avidin or streptavidin molecule.

With a biotin group on each end of the dPEG®3 spacer, PN10325 can bind to two different avidin/streptavidin binding sites, both intramolecularly and intermolecularly. Indeed, this product was developed specifically to block endogenous biotin found in all cells and tissues so that it did not interfere with targeted biotin-streptavidin interactions in therapeutic and diagnostic applications where endogenous biotin was known to cause problems. PN10325 was found to bind, on average, three biotin-binding sites on streptavidin – two intramolecularly and one intermolecularly.

The binding behavior of PN10325 with streptavidin opens up possible uses for the product in the self-assembly of supramolecular constructs and signal amplification. In the first example, if two parts of a potential supramolecular construct both contain avidin or streptavidin, addition of PN10325 under empirically determined optimized conditions could trigger self-assembly of the construct as the bis-dPEG®3-biotin binds to the separate avidin or streptavidin molecules in the two halves of the construct. In the second example, multiple streptavidin molecules conjugated to horseradish peroxidase (HRP) could be bound together with a streptavidin-biotinylated protein complex (for example, a biotinylated antibody), thus amplifying the signal from HRP. Undoubtedly, our customers can find even more creative ways to use this product to best advantage.

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