Affinity purified Solanum tuberosum lectin/agglutinin (STA/STL) is a hydroxyproline-rich glycoprotein. This lectin contains 50% carbohydrates, predominantly arabinose; and consists of two subunits. STA/STL binds oligomers of N-acetylglucosamine and some bacterial cell wall oligosaccharides containing N-acetylglucosamine and N-acetylmuramic acid. N-acetyllactosamine is a relatively weak inhibitor of hemagglutination induced by this lectin; though, it does not have a blood group specificity. Solanum tuberosum lectin has been shown to bind two and a half times more to colon cancer cells than normal tissue.
Alkaline phosphatase (AP) is conjugated to Solanum tuberosum Lectin (STA/STL) to show the binding of STA/STL 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.