N-Biotinyl p-aminophenyl arsenic acid is a bifunctional reagent that can bind to both streptavidin and dithiols. N-Biotinyl p-aminophenyl arsenic acid decreases the Rbungarotoxin-binding sites in reduced Torpedo nicotinic receptors (IC50 is 10-300 nM), and protects the receptor from irreversible alkylation by bromoacetylcholine.
References:
[1]. Moaddel R, et al., Novel biotinylated phenylarsonous acids as bifunctional reagents for spatially close thiols: studies on reduced antibodies and the agonist binding site of reduced Torpedo nicotinic receptors. Bioconjug Chem. 1999 Jul-Aug;10(4):629-37.