title: Intermolecular interaction of avidin and PEGylated biotin.
abstract: The equilibrium binding constants and stoichiometries between PEGylated biotins and avidin have been studied for a range of PEGylated biotin molecular weights. These studies show that as the molecular weight of PEG (polyethylene glycol) increases over the range 588, 3400, and 5000 g/mol, the equilibrium dissociation constants of PEGylated biotins with avidin increase to approximately 10 (-8) M compared with 10 (-15) M for the biotin-avidin complex. The stoichiometries of PEGylated biotins with avidin are 4:1 for 588 and 3400 g/mol PEG and 1:1 for 5000 g/mol PEG. The data demonstrate that the equilibrium binding constant and the stoichiometry of the avidin-biotin-PEG complex system can be adjusted by the length of PEG chains. This approach may be used with PEGylated biotin analogues for pretargeting in drug delivery, such as a biotin-PEGylated enzyme for converting an inactive prodrug into a cytotoxin. When a PEG chain is chosen as an appropriate spacer, the length of the PEG chain must be considered because PEG can block the binding sites on avidin.
authors.affiliation: Department of Chemistry, University of Wisconsin Madison, Madison, WI 53706-1322, USA.
authors.forename: Shan
authors.initials: S
authors.lastname: Ke
authors.forename: John C
authors.initials: JC
authors.lastname: Wright
authors.forename: Glen S
authors.initials: GS
authors.lastname: Kwon
mesh_terms: D001360:Avidin / Q000737:chemistry*; D001710:Biotin / Q000737:chemistry*; D007097:Imines / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry*
chemical_list: D007097:Imines; D001360:Avidin; D011092:Polyethylene Glycols; D001710:Biotin