Datura stramonium agglutinin or lectin (DSA/DSL) is purified by affinity chromatography. Seeds of Datura stramonium contain at least three different carbohydrate-binding proteins, and the most prominent lectin is a dimeric glycoprotein composed of two nonidentical subunits that contains 40% carbohydrate. It binds well to N-acetylglucosamine, oligomers, and branched pentasaccharide, including two N-acetylglucosamine disaccharides linked to mannose (β-1,6) and (β-1,2), which is known to be the most potent inhibitor of agglutination. DSL prefers binding to (GlcNAc)2-4 and elutes with the sugar chitin hydrolysate. DSL binds well in the acidic pH range and its affinity decreases above pH 8.0. This agglutinin has blood group A, B, and O specificity. Studies have shown that DSA can act as a biomarker for neoplastic urotherial cells.
Alkaline phosphatase (AP) is conjugated to Datura stramonium Lectin (DSA/DSL) to show the binding of DSA/DSL in many applications including Western blotting and ELISA. Alkaline phosphatase is a large protein (140 kDa) that catalyzes the hydrolysis of phosphate groups from a substrate resulting in a colored or fluorescent product. The optimal enzymatic activity of this protein is between pH 8 and 10, and its reaction rate remains linear, improving sensitivity over time.