Secondary Antibody Detection Probes

The interaction of biotin and biotin binding protein has been a useful tool in protein and nucleic detection and purification. A variety of molecules, including lectins, proteins, and antibodies, can be biotinylated and used as primary probes for detection with avidin or streptavidin. These molecules can react with binding protein labeling probes such as avidin or streptavidin as secondary probes or other detection reagents for use in biological assays such as:

• Protein detection
• Nucleic acid detection
• Protein Isolation and enrichment
• Protein Interaction

Binding Characteristics of Biotin-Binding Proteins
Streptavidin, avidin and NeutrAvidin biotin-binding proteins each bind four biotins per molecule with high affinity and specificity. Their multiple binding sites permit a number of techniques in which unlabeled avidin, streptavidin or NeutrAvidin biotin-binding protein can be used to bridge two biotinylated reagents. This bridging method, which is commonly used to link a biotinylated probe to a biotinylated enzyme in enzyme-linked immunohistochemical applications, often eliminates the background problems that can occur when using direct avidin or streptavidin-enzyme conjugates. The table below is a comparison of each binding protein we offer.

We offer three different kinds of biotin-binding proteins:

Properties of Biotin-Binding Proteins

Avidin Streptavidin NeutrAvidin Protein Molecular Weight 67K 53K 60K Biotin-binding Sites 4 4 4 Isoelectric Point (pl) 10.5 6.8-7.5 6.3 Specificity Low High Highest Affinity for Biotin (Kd) 10-15 M 10-15 M 10-15 M Nonspecific Binding High Low Lowest

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