SA10 Streptavidin is our longest-established streptavidin product, being a widely-used workhorse of the industry for over 25 years. It is purified to a high degree from fermentations of Streptomyces avidinii and has a molecular weight of 52 kDa (also known as 'core' streptavidin).
We also offer a variant of streptavidin (SA26 Streptavidin-plus), which is made as a recombinant form in E. coli and has a molecular weight of 55 kDa. Streptavidin-plus has been found to have superior performance in certain applications, such as when immobilized as an ELISA capture agent. The specific activity of SA10 is ≥14.0 U/mg protein, and that of SA26 is ≥15.0 U/mg protein, when measured by the industry-standard HABA dye-binding assay. The specific activity measurement is higher still when measured by the alternative biotin-titration assay used by some suppliers.
These streptavidin products are available in various pack sizes and are supplied lyophilized. If you require a sample to test in your application, please contact Agilent.