Streptavidin Purified

Streptavidin is a biotin binding protein present in the fermentation broth of the bacterium Streptomyces avidinii. Each molecule of streptavidin can bind four molecules of biotin with a high affinity constant (K_d~10 ^-15). Unlike native avidin, streptavidin is not glycosylated and has a near neutral isoelectric point (pI ~ 5-6) vs a pI of 10 for native avidin.

Streptavidin is lyophilized under slight alkaline conditions from deionized water. The final lyophilized protein contains approximately 10% NaCl.

Reconstitute in highly pure deionized water to 1-15 mg/ml. If buffering is required, add sufficient stock solution of 10-20X phosphate buffered saline (PBS) to bring the final concentration to 1X PBS. Do not reconstitute directly in PBS.

The lyophilized streptavidin is stable for at least one year when stored desicated at –20°C. It is recommended to only reconstitute the amount required for use. However, any unused reconstituted streptavidin should be aliquoted in working volumes without diluting and stored at –20°C in a manual defrost freezer. Avoid Repeated Freeze Thaw Cycles.

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