Several sources indicate that, once bound, the streptavidin-biotin complex can withstand up to 2% SDS and 6M urea (at room temperature). However, I can't find any discussion on whether the presence of SDS or urea in the sample buffer would inhibit binding in the first place. There is some evidence that urea weakly binds the streptavidin binding site. Most protocols reduce SDS to 0.1% or less, and I have found none that include urea.
Hi Kristian,
streptavidin is a tetramer and biotin binds in the interface between subunits. Thus, everything that will affect the tetrameric structure of streptavidin is likely to reduce its binding capacity for biotin. As always, effects depend on the concentration and exact methodology used. While a low concentration of SDS and urea may be compatible with biotin binding, concentrations that will denature streptavidin or cause the tetramer to fall apart will not allow the binding of biotin. To be on the safe side, I would try to avoid both. If this is not an option, I would go ahead and try to dilute your sample before loading. This does not mean that urea is a priori a bad for streptavidin. Actually, monomeric avidin (with reduced binding affinity to biotin, allowing biotin to be released under mild conditions) is produced by washing immobilized avidin with guanidinium hydrochloride (which has a similar effect on proteins as urea).
Best wishes
Using highly sensitive and quantitative radioimmunoassay procedures we have measured the effects of different concentrations of three commonly used detergents, SDS, DOC, and Triton X-100, on antibody-antigen reactions. Triton X-100 had a relatively mild effect on primary antigen-antibody bindings, the precipitin reaction, and a double antibody RIA as evidenced by only an 8 to 10% inhibition of binding or precipitation. These results were not detergent concentration dependent, as Triton concentrations ranging from 5 to 0.1% had virtually no differential effects. Sodium deoxycholate (DOC) had a more profound effect on both primary antigen-antibody binding and the precipitin reaction than did Triton X-100, and its effects, unlike those of Triton X-100, were concentration dependent. There was a direct relationship between concentration of DOC and degree of inhibition of both primary binding and immune precipitation especially in antigen excess. Sodium dodecylsulfate (SDS), at concentrations 10- to 100-fold less than either Triton X-100 or DOC, had profound inhibitory effects on primary antigen-antibody binding, the precipitin reaction, and a double antibody radioimmunoassay. Generally, at concentrations greater than 0.01% SDS, almost all immunochemical reactivity is destroyed. (Effects of Ionic and Nonionic Detergents on Antigen-Antibody Reactions
Louis F. Qualtiere, Amil G. Anderson and Paul Meyers)
I recently found these papers which might be relevant to solve your question:
Kurzban, G., Bayer, E., Wilchek, M., Horowitz, P. (1991). The quaternary structure of streptavidin in urea. The Journal of biological chemistry 266(22), 14470-7. https://www.ncbi.nlm.nih.gov/pubmed/1860855 Bayer, E., Ehrlich-Rogozinski, S., Wilchek, M. (1996). Sodium dodecyl sulfate-polyacrylamide gel electrophoretic method for assessing the quaternary state and comparative thermostability of avidin and streptavidinElectrophoresis 17(8), 1319-1324. https://dx.doi.org/10.1002/elps.1150170808 Waner, M., Navrotskaya, I., Bain, A., Oldham, E., Mascotti, D. (2004). Thermal and Sodium Dodecylsulfate Induced Transitions of Streptavidin Biophysical Journal 87(4), 2701-2713. https://dx.doi.org/10.1529/biophysj.104.047266
I hope it helps!!
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