Streptavidin–Horseradish Peroxidase (Streptavidin-HRP) is a conjugated protein reagent widely used for detection and signal amplification in immunoassays and molecular biology applications. It consists of streptavidin, a tetrameric biotin-binding protein originally derived from Streptomyces avidinii, chemically linked to the enzyme horseradish peroxidase (HRP). Streptavidin binds biotin with extremely high affinity, allowing Streptavidin-HRP to specifically detect biotinylated antibodies, proteins, nucleic acids, or other biomolecules. The HRP enzyme catalyzes the oxidation of chromogenic, chemiluminescent, or fluorogenic substrates—such as TMB, DAB, or luminol—producing a detectable signal that enables sensitive visualization or quantification of target molecules. Streptavidin-HRP is commonly used in laboratory assays including enzyme-linked immunosorbent assays (ELISA), Western blotting, immunohistochemistry (IHC), and nucleic acid hybridization assays. Through the strong streptavidin–biotin interaction and enzymatic signal generation, Streptavidin-HRP provides highly sensitive and specific detection of biotin-labeled targets in cell culture studies, diagnostic assays, and biomedical research.