Streptavidin, lyophilized (not suitable for Strep-tag® applications):
Streptavidin is a tetrameric protein composed of identic subunits. Each subunit binds one biotin molecule with a KD of ~1x10-15 M. The preparation contains an N- and C-terminal shortened variant (core streptavidin) with improved properties concerning homogeneity, solubility, resistance towards proteolytic degradation and accessibility of the biotin binding pocket as compared to native streptavidin.
Specifications
Form
Lyophilized in 10 mM potassium phosphate buffer pH 6.5
MW per tetramer
~53 000
Extinction coefficient per subunit
ε280 = 41326 M-1 cm-1
Specific activity
> 17 U/mg (one unit binds 1 µg D-biotin)
Purity
> 95 % as estimated by SDS-PAGE
Proteolytic activity
< 10-3 U/mg protein (Azocoll, 25 °C, 24 h, pH 8.0)
Reconstitution
Dissolve with water
Storage (lyophilized)
-20 °C
Stability (lyophilized)
2 years after shipping
Storage (dissolved)
4 °C; for longer storage in dissolved form add 1 mM EDTA and/or 0.02 % NaN3 or pass the solution through a sterile filter
Shipment
Room temperature
Quality control by SDS-PAGE:
P1 = 50 µg Streptavidin, boiled
M = marker (~ 0.5 µg per band)
