An Alkaline Phosphatase Lacking Wheat Germ Agglutinin Binding Sites; Useful Enzyme for Lectin Assays with Comparable Activity to the Calf Enzyme

Despite the availability of various alkaline phosphatase (ALP) isoenzymes, the calf enzyme is being used in current enzyme assays as the detector enzyme. The glycosylation pattern of this enzyme makes it a suitable ligand for binding to wheat germ agglutinin lectin (WGA). As a result of this property, the enzyme can not be used as a conjugate with this lectin, and the calf enzyme conjugates can not be used when lectin is on the solid phase in lectin based ELISA systems. The purpose of this study was to evaluate the activity and lectin binding property of an ALP from the hepatopancreas of shrimp Pandalus borealis as an alternative for the calf enzyme. While the problem of non-specific binding to WGA lectin was circumvented with the shrimp enzyme, the activity of the new studied enzyme was seen to be higher than the calf enzyme. Studies of the effect of magnesium ion concentration on both enzymes demonstrated a major effect of the cation on shrimp enzyme and a relatively minor effect on the calf ALP. Conjugation of the shrimp ALP with streptavidin can be used in enzyme amplification technique in lectin based ELISA using WGA.