Recombinant Streptomyces avidinii Streptavidin is produced in E.coli and contains the full length mature protein, spanning amino acids 25-183. The protein carries an N-terminal GST tag for easier purification and detection. SDS-PAGE analysis confirms purity levels above 90%, which appears to make it suitable for research applications that demand high-quality protein standards.
Streptavidin from Streptomyces avidinii has gained popularity in research primarily because of its strong affinity for biotin. This interaction forms one of the strongest known non-covalent bonds. Such robust binding makes the protein particularly valuable in biochemical assays - especially those involving purification, detection, and immobilization of biotinylated molecules. The protein's ability to mediate these interactions may explain its widespread adoption in molecular biology and biotechnology research.
Potential Applications
Note: The applications listed below are based on what we know about this protein's biological functions, published research, and experience from experts in the field. However, we haven't fully tested all of these applications ourselves yet. We'd recommend running some preliminary tests first to make sure they work for your specific research goals.
Streptavidin from Streptomyces avidinii is a bacterial protein that naturally forms a tetramer with extremely high biotin-binding affinity. The E. coli expression system is generally compatible with bacterial proteins, and streptavidin has been successfully expressed in E. coli in many studies. However, the N-terminal GST tag (∼26 kDa) is significantly larger than the streptavidin monomer (∼13 kDa) and may sterically interfere with proper tetramer formation, which is essential for high-affinity biotin binding. While the protein may be soluble, the probability of correct tetramerization and functional activity is moderate but requires experimental validation due to potential tag interference.
1. Biotin-Binding Affinity Studies
This application is conditionally suitable but requires validation. If the protein achieves proper tetramerization despite the GST tag, it could be used for biotin-binding studies. However, the large GST tag may sterically hinder the biotin-binding pocket or prevent correct tetramer formation, leading to significantly reduced binding affinity or false-negative results. Surface plasmon resonance or fluorescence polarization assays should include positive controls to validate binding capability.
2. GST Pull-Down Assay Development
This application is highly suitable as it leverages the GST tag directly. The protein can be immobilized on glutathione resins to capture biotinylated molecules. Even if biotin-binding affinity is reduced, the GST tag functionality remains intact for pull-down applications. This approach is valuable for isolating biotinylated targets from complex mixtures.
3. Comparative Structural and Biochemical Analysis
This application is conditionally suitable for biochemical comparisons but is limited for structural studies. The GST tag may alter thermal stability and oligomeric state measurements. Comparative analyses should focus on sequence-based comparisons rather than structural or functional comparisons with native streptavidins.
4. Biotinylation System Validation
This application is not recommended without prior validation of biotin-binding functionality. If the protein has impaired biotin binding due to the GST tag, it will yield false-negative results in validation assays. A tag-free streptavidin control is essential for reliable validation.
Final Recommendation & Action Plan
This GST-tagged streptavidin is primarily suitable for applications leveraging the GST tag functionality but requires rigorous validation for biotin-binding studies. The immediate priority is to test biotin-binding activity using a standard assay (e.g., HABA assay or SPR) to determine if the tag interferes with function. If binding activity is confirmed, proceed with Application 1 cautiously. Application 2 (GST pull-downs) can proceed immediately regardless of biotin-binding status. Application 3 should be limited to sequence-based comparisons. Avoid Application 4 unless biotin-binding is validated. For critical biotin-binding applications, consider tag removal or use commercial tag-free streptavidin. This systematic approach ensures appropriate use based on functional validation.
