Avidinstreptavidin

Avidinstreptavidin is a term that appears to be a misspelling or a non-standard combination of "avidin" and "streptavidin". Avidin and streptavidin are both proteins that have a very high affinity for biotin, a vitamin also known as B7. This strong binding property makes them invaluable tools in various biological and biochemical applications, particularly in molecular biology and diagnostics.

Avidin is a glycoprotein found in egg whites of birds, reptiles, and amphibians. Streptavidin, on the other hand, is a tetrameric protein produced by the bacterium Streptomyces avidinii. While both bind biotin with remarkable strength, streptavidin generally exhibits a lower non-specific binding to other molecules compared to avidin, making it a preferred choice in many sensitive assays.

The avidin-biotin or streptavidin-biotin interaction is one of the strongest known non-covalent biological interactions. This high affinity is exploited by conjugating avidin or streptavidin to reporter molecules such as enzymes, fluorescent dyes, or magnetic beads. These conjugates can then be used to detect or isolate specific biomolecules that have been labeled with biotin. Applications include ELISA (enzyme-linked immunosorbent assay), Western blotting, immunohistochemistry, and affinity purification of proteins. The specificity and robustness of this binding system contribute significantly to the sensitivity and accuracy of these techniques.