PEGylated streptavidin, custom synthesis. One, two, four or eight streptavidin molecules can be attached to a linear mPEG, linear PEG, 4-arm or 8-arm PEG, respectively with the option of all available PEG molecular weights. Streptavidin is a 52.8 kDa protein and has an extraordinarily high affinity for biotin (also known as vitamin B7 or vitamin H). With a dissociation constant (Kd) on the order of 10âˆ’14 mol/L, the binding of biotin to streptavidin is one of the strongest non-covalent interactions known in nature.
Reference: 1) Green, NM (1975). "Avidin". Advances in protein chemistry 29: 85â€“133, Text.