Streptavidin is a ∼60 kDa homotetramer. Streptavidin binds four molecules of biotin with the highest affinity. The binding affinity of biotin to streptavidin is one of the highest reported for a non-covalent interaction to date, with a KD ∼ 0.01 pM. Streptavidin has an immunosuppressive role.
Streptavidin (2-200 μg/mL) significantly suppresses the proliferation of Lewis T cells to WF by 76%-83% compared with untreated responders[1].
Streptavidin (8-80 mg/kg) treatment is effective in prolonging rat cardiac allografts in the high-responder WF-to-Lewis combination[2].
[1]. Keleabetswe L. Mpye , et al. The effects of temperature on streptavidin-biotin binding using affinity isothermal titration calorimetry. AIMS Biophysics. 2020, 7(4): 236-247.
[2]. P Witkowski, et al. Effect of streptavidin on cardiac allograft prolongation is due to host T-Cell suppression. Transplant Proc. Jan-Feb 2005;37(1):116-8.