Alkaline phosphatases are non-specific membrane-bound phosphomonoesterases that catalyze the hydrolysis reaction via a phosphoseryl intermediate to produce inorganic phosphate and the corresponding alcohol, optimally at high pH. Alkaline phosphatase exists as a dimer, each monomer binding 2 zinc atoms and one magnesium atom, which are essential for enzymatic activity. Mammalian alkaline phosphatase is divided into four isozymes depending upon the site of tissue expression. They are Intestinal ALP, Placental ALP, Germ cell ALP and tissue nonspecific alkaline phosphatase or liver/bone/kidney (L/B/K) ALP.
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