Streptavidin is a homotetrameric protein that can bind up to 4 molecules of biotin with high affinity.
Core streptavidin removes the unrelated sequences and retain its core sequence for better stability and solubility.
Core streptavidin-2 has weaker affinity with biotin (Kd≈10-7M) and allows recycles of cSA-2.
Core streptavidin-4 allows 2 to 4 binding ratio of biotin, allows more stable binding for research and diagnostic purpose.
