Thermo Scientific Pierce Sulfo-SBED Biotin Labeling Transfer Reagent is a versatile reagent used to label purified proteins and then The attached biotin tag is covalently transferred to specific interactors of the protein.

Sulfo-SBED is sulfo-N-hydroxysuccinimide-2-(6-[biotinamido]-2-(p-azidobenzamido)-hexanoamido ) Abbreviation for ethyl-1,3'-dithiopropionate. It is a heterobifunctional chemical cross-linker that can be covalently linked to a primary amine on one end and to almost any protein functional group on the other end. Unlike typical cross-linkers, Sulfo-SBED also includes a biotin group and a cleavable disulfide spacer arm. The combination of these features allows the cross-linker to sequentially cross-link interacting proteins and transfer the biotin affinity tag from one protein (i.e., the purified "bait" protein) to another protein (possibly an unknown "prey" protein) . Label transfer is a powerful in vitro method for studying protein interactions. An increasing number of publications describe the use of Sulfo-SBED biotin label transfer reagents to identify previously unknown binding partners for protein interactions and to more fully characterize specific protein binding domains of other protein interactions.

Typical protocol for label transfer experiments:

• Add a few microliters of dissolved Sulfo-SBED reagent to 0.5-1 mL of purified bait protein in PBS in solution.
•Incubate the mixture on ice or in the dark at room temperature for 30-120 minutes.
• Perform desalting or dialysis (under low light) to remove excess unreacted Sulfo-SBED from the labeled bait protein.
•Add labeled bait proteins to cell lysates or other solutions containing putative target protein interactors ("prey").
•When the interacting complex forms, expose the solution to UV light (365 nm) for a few minutes.
•Analyze products by one of several methods:
•Western Blotting: Cleave cross-links in DTT, separate proteins by SDS-PAGE, and Western blot using horseradish Biotinylated bands were detected with peroxidase-labeled streptavidin.
•Purification and mass spectrometry or sequencing: Affinity purification of biotinylated proteins or peptide fragments is performed after trypsin digestion, and MS or sequencing is performed to characterize the related proteins.

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Sulfo-SBED biotin label transfer Kit - Western Blotting Application