StreptavidinFor improved detection sensitivity, steptavidin-based amplification techniques are widely used in flow cytometry, fluorescent imaging, western blotting or microplate-based detection. Fluorescent conjugates of streptavidin are used to detect biotinylated biomolecules such as primary and secondary antibodies, ligands and toxins or DNA probes for in situ hybridization. Streptavidin-conjugated magnetic beads can be used to isolate proteins, cells, DNA as well as be used in immunoassays or biopanning.

The family of biotin-binding proteins includes streptavidin, avidin, and NeutrAvidin® protein. Each protein binds four biotins per molecule with high affinity and selectivity. The most commonly used is streptavidin, which is non-glycosylated and exhibits low levels of nonspecific binding. Avidin is a highly cationic glycoprotein with an isoelectric point of about 10.5. Its positively charged residues and oligosaccharide component can interact nonspecifically, causing background problems in some applications. NeutrAvidin® protein has been processed to remove the carbohydrate and lower its isoelectric point, which can result in reduced background staining.

Apoptosis  Assays for Flow Cytometry   In addition to Qdot® probes and AlexaFluor® dyes, Life Technologies provides a range of streptavidin conjugates optimized for use in flow cytometry including R-PE and tandem conjugates.
  Streptavidin-coupled Dynabeads® are widely used for bead-based magnetic capture of any biotinylated molecule (e.g., cells, proteins, nucleic acids) in a variety of manual and automated applications.
Apoptosis  Assays for Flow Cytometry For ultrasensitive detection on western blots, Life Technologies' WesternDot™ 625 Western Blot Kits combine Qdot® 625 nanocrystals with a high-affinity streptavidin-biotin amplification step.
Cell Viability Assays for Flow Cytometry   Use these tools to select the optimal technique for your target abundance with complementary detection wavelengths that enable you to multiplex your experiment.