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Enzyme Streptavidin Conjugates |
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Streptavidin is a 60,000 dalton protein composed of four identical subunits, each of which has a binding site for biotin. Isolated from the microorganism Streptomyces avidinii, this protein resembles egg white avidin in its biotin binding properties. Its affinity for biotin is
several orders of magnitude lower than egg white avidin, it lacks carbohydrate, and has a lower isoelectric point than avidin. Streptavidin generally requires a longer spacer arm between the biotin residues and the protein or probe to which it is attached and it is less stable than avidin. In spite of these differences, in most applications, streptavidin and avidin conjugates are interchangeable.
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