Erythrina cristagalli lectin or agglutinin (ECL/ECA) is affinity purified lectin consists of two subunits with molecular weights of 28,000 and 26,000. ECL binds to carbohydrate structure in membrane and serum glycoproteins of mammalian cells. The shape of the lectin binding domains may resemble cavity type with Galβ1->4GlcNAc as the core binding site with additional one to four sugar subsites and is most complementary to a linear trisaccharide. Some Galβ1-related oligosaccharides are the major structures for lectin binding. Lectin binding activity can be abolition through salic acid substitution. This allows for specificity to fractionate and isolate mammalian glycoproteins.
Alkaline phosphatase (AP) is conjugated to Erythrina cristagalli (Coral tree) Lectin (ECL/ECA) to show the binding of ECL/ECA 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.