Traptavidin is the S52G, R53D mutant of streptavidin, the high affinity biotin binding protein. Useful in various imaging, protein purification, and nano-assembly applications.
Streptavidin binds biotin-conjugates with exceptional stability, but dissociation does occur and can be limiting in imaging, DNA amplification, and nanotechnology. This Traptavidin protein overcomes these limitations with a ~10-fold slower biotin off-rate, increased mechanical strength, and improved thermostability compared to streptavidin.
From the laboratory of Mark Howarth, PhD, University of Oxford.
|Source:||Recombinant, expressed in E. coli|
|Molecular Weight:||13.2 kDa (without boiling, traptavidin will run on SDS-PAGE as a tetramer and remain bound to biotin)|
|Amino Acid Sequence:||AEAGITGTWYNQLGSTFIVTAGADGALTGTYESAVGNAEGDYVLTGRYDSAPATDGSGTALGWTVAWKNNYRNAHSATTWSGQYVGGAEARINTQWLLTSGTTEANAWKSTLVGHDTFTKVKPSAAS|
|Purity:||>98% by SDS PAGE (Purified from inclusion body refolding with selective ammonium sulfate precipitation and then iminobiotin-agarose affinity chromatography.)|
|Buffer:||Phosphate buffered saline (PBS) pH 7.4; The protein is highly stable and should be compatible with a wide range of salts, ionic strengths and pH values (certainly 5-9), as well as DMF or DMSO up to 10%.|
|Concentration:||2.11 mg/mL (40 uM tetramer) in PBS.|
|Comments:||10-fold lower off-rate from biotin and biotin conjugates compared to streptavidin. Increased thermal stability and mechanical stability of biotin binding.|
|Storage:||-80°C, stable for 1-2 weeks when kept at 4°C (avoid multiple freeze-thaw cycles)|
Purity, Binding, and Thermostability of Traptavidin Protein
(A) SDS-PAGE analysis of purified Traptavidin protein after boiling. (B) Off-rate for biotin-4-fluorescein at 37°C (mean ± 1 s.d.). (C) Thermostability of biotinylated DNA binding: Streptavidin/Traptavidin-bound DNA heated at indicated temp. for 3 min, in presence of competing free biotin, before agarose gel electrophoresis.
Traptavidin has a reduced on-rate compared to streptavidin, depending on the nature of the biotin conjugate; binding should still be rapid when working with high concentrations of biotinylated target, but for binding sub-micromolar concentrations of biotinylated target then longer should be allowed for binding than would be required for streptavidin.
Theoretical pI for traptavidin: 5.1 (6.1 for streptavidin)
Extinction coefficient (from ProtParam) at 280 nm: 41,940 M-1cm-1
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