Alkaline phosphatase (AP) is a homodimeric enzyme complex that is commonly found in a wide range of organisms, from bacteria to all tissues of the human body. AP is a zinc metalloenzyme (1), in which metal ions play a key role in the regulation of catalytic activities and stabilization of enzyme-substrate complex. As proposed by Gettins and Coleman using NMR studies (10), each active site of AP comprises of three metal binding sites, which acknowledged as M1, M2, and M3. Two zinc ions bind to the M1 and M2 sites while a magnesium ion occupies M3. Zn ions are necessary for AP to function effectively in order to activate the binding of phosphate and forming of phosphoseryl intermediate (1). Replacing Zn ions with other divalent cations will lower
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It is only found on the outside of cells and is attached to the outer surface of the plasma membrane through a glycosylphosphatidylinositol that covalently bind to the C-terminus carboxyl group of the enzyme (8). The total number of structural genes that code for various forms of human AP is unknown, but there are at least three structural genes, each with a specific function: one codes for intestinal AP, one for placental, and another for kidney, liver and bones (3,4). The molecular weights of human AP are different depending on where it originates in the body. For instance, human placental AP has a molecular mass of 132kDa, and each subunit weighs 66kDa while liver AP assumes to be 160kDa (2). Although the physiological functions of the isozymes are still not known at present, the level of alkaline phosphatase in the bloodstream can be a valuable indicator to diagnose liver and bone diseases. In addition, mutations in structural gene that encodes AP can result in Hypophosphatasia. Hypophosphatasia is a metabolic disease that disrupts the process of mineralization by interfering with the uptake of phosphorus and calcium into bones and
It is only found on the outside of cells and is attached to the outer surface of the plasma membrane through a glycosylphosphatidylinositol that covalently bind to the C-terminus carboxyl group of the enzyme (8). The total number of structural genes that code for various forms of human AP is unknown, but there are at least three structural genes, each with a specific function: one codes for intestinal AP, one for placental, and another for kidney, liver and bones (3,4). The molecular weights of human AP are different depending on where it originates in the body. For instance, human placental AP has a molecular mass of 132kDa, and each subunit weighs 66kDa while liver AP assumes to be 160kDa (2). Although the physiological functions of the isozymes are still not known at present, the level of alkaline phosphatase in the bloodstream can be a valuable indicator to diagnose liver and bone diseases. In addition, mutations in structural gene that encodes AP can result in Hypophosphatasia. Hypophosphatasia is a metabolic disease that disrupts the process of mineralization by interfering with the uptake of phosphorus and calcium into bones and