Streptavidin is a protein that has similar binding properties to avidin. It is isolated from Streptomyces Avidinii. Streptavidin has a molecular weight of 60 KD and has 4 subunits. Each subunit can bind one molecule of biotin. Biotin is a 244 dalton water-soluble vitamin. Streptavidin has an extremely high binding affinity (Kd=10-15) for biotin.
Streptavidin-HRP (M00091) is coupled steptavidin with horseradish peroxidase (HRP). This highly sensitive detector conjugate binds to biotinylated primary or secondary antibodies in enzyme immunoassay, immunoblotting, immunohistochemistry, flow cytometry, hybridoma screening systems. This conjugate also binds to nucleic acids labeled with biotinylated nucleotide analogs in Southern or Northern blot.