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Protocol
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Streptavidin (MW ~55,000 Daltons) is a tetrameric protein isolated from Streptomyces avidinii, which specifically binds biotin (244 Daltons). The binding between streptavidin and biotin is one of the strongest non-covalent bindings known at (Kd) of ~10-14 Mol/L (biotin-streptavidin complex). Unlike avidin, streptavidin in non-glycosylated, and is mildly acidic (pI~5.5), whereas avidin is basic (pI~10.5). Because streptavidin lacks glycosylated moieties and has a lower pI then avidin, streptavidin has considerably less non-specific binding which results in less background signal in many tests. These characteristics make streptavidin an ideal choice for a variety of applications including studies with cells, nucleic acids, drugs, small/large molecules, peptides, and proteins.
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