How many biotin binding-sites are there per streptavidin molecule?
• Streptavidin is a protein composed of four identical subunits, each containing a high affinity binding site for biotin (KD = 10-15 M). Streptavidin has the same biotin binding properties as avidin, but it has a low isoelectric point (pI=5) and no carbohydrate groups, resulting in low nonspecific binding.
