title: Noncooperativity of biotin binding to tetrameric streptavidin.
abstract: Streptavidin tetramers have been separated according to their biotin content by anion exchange chromatography. Biotin-free and biotin-saturated streptavidin were coincubated. Streptavidin at intermediate ligation levels, i.e., with one, two, or three molecules of bound biotin, accumulates over time. A steady state distribution of ligation levels is reached after 2 days. When biotin was allowed to redistribute starting from homogeneous populations containing two molecules of biotin per tetramer, a similar steady state distribution of ligation levels was observed, thereby demonstrating an equilibrium distribution. Quantification of this equilibrium indicates that biotin binds to streptavidin with no cooperativity.
authors.affiliation: Department of Biochemistry and Molecular Biology, Georgetown University Medical Center, Washington, DC 20007-2197, USA.
authors.forename: M L
authors.initials: ML
authors.lastname: Jones
authors.forename: G P
authors.initials: GP
authors.lastname: Kurzban
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D001665:Binding Sites; D001667:Binding, Competitive; D001710:Biotin / Q000378:metabolism*; D002852:Chromatography, Ion Exchange; D066298:In Vitro Techniques; D007700:Kinetics; D008024:Ligands; D011485:Protein Binding; D011487:Protein Conformation; D019809:Streptavidin
chemical_list: D001426:Bacterial Proteins; D008024:Ligands; D001710:Biotin; D019809:Streptavidin