膜杰作
Star Staining
分子别名（Synonym）
Streptavidin,SA
表达区间及表达系统（Source）
Streptavidin Protein-Alexa Fluor 647 (STN-NA119) is expressed from E. coli cells.
蛋白结构（Molecular Characterization）
This protein carries no "tag".
The protein has a calculated MW of 13.8 kDa. The protein migrates as 12-15 kDa when calibrated against Star Ribbon Pre-stained Protein Marker under reducing (R) condition (SDS-PAGE).
偶联（Conjugate）
AF647
Excitation Wavelength: 640 nm
Emission Wavelength: 672 nm
标记（Labeling）
The primary amines in the side chains of lysine residues and the N-terminus of the protein are conjugated with AF647 using standard chemical labeling method. The residual AF647 is removed by molecular sieve treatment during purification process.
蛋白标记度（Protein Ratio）
The AF647 to protein molar ratio is 3-6.
纯度（Purity）
>95% as determined by SDS-PAGE.
>90% as determined by SEC-HPLC.
制剂（Formulation）
Lyophilized from 0.22 μm filtered solution in PBS, pH7.4 with trehalose as protectant.
Contact us for customized product form or formulation.
重构方法（Reconstitution）
Please see Certificate of Analysis for specific instructions.
For best performance, we strongly recommend you to follow the reconstitution protocol provided in the CoA.
存储（Storage）
For long term storage, the product should be stored at lyophilized state at -20°C or lower.
Please protect from light and avoid repeated freeze-thaw cycles.
This product is stable after storage at:
- -20°C to -70°C for 12 months in lyophilized state;
- -70°C for 3 months under sterile conditions after reconstitution.
电泳（SDS-PAGE）
Streptavidin Protein-Alexa Fluor 647 on SDS-PAGE under reducing (R) condition. The gel was stained with Coomassie Blue. The purity of the protein is greater than 95% (With Star Ribbon Pre-stained Protein Marker).
SEC-HPLC
The purity of Streptavidin Protein-Alexa Fluor 647 (Cat. No. STN-NA119) was greater than 90% as determined by SEC-HPLC.
活性（Bioactivity）-FACS
5e5 of Jurkat cells were stained with 100 μL of 3 μg/mL of Biotinylated Anti-Human CD3 Antibody, Mouse IgG2a,Avitag (Clone: OKT3), premium grade and isotype control antibody respectively, washed and then followed with 100 μL of 1 μg/mL of Streptavidin Protein-Alexa Fluor 647 (Cat. No. STN-NA119) and analyzed with FACS. Alexa 647 signal was used to evaluate the binding activity (Routinely tested).
Protocol
背景（Background）
Streptavidin is a tetrameric protein purified from the bacterium Streptomyces avidinii, and exhibits high binding affinity for biotin. Able to bind one molecule of biotin with each subunit. Streptavidin (PI=6.0-7.5) has lower level of non-specific binding to various biological components at physiological pH than avidin (PI=7.4), resulting from its isoelectric point (PI).Streptavidin is useful in affinity chromatography, ELISA, immunohistochemistry and Western Blotting.
