Steptavidin, a bacterial protein isolated from Streptomyces avidinii, is similar to egg-white avidin in its ability to bind biotin, and has been used as a replacement for egg-white avidin because of its more favorable chemical properties.Conjugates of streptavidin are recommended for use with Biotin-SP-conjugated antibodies and Biotin-SP-conjugated ChromPure proteins. Buffer: 0.01M Sodium Phosphate, 0.25M NaCl, pH 7.6 Stabilizer: 15 mg/ml Bovine Serum Albumin (IgG-Free, Protease-Free) Preservative: None (Warning: Use of sodium azide as a preservative will substantially inhibit the enzyme activity of horseradish peroxidase.)