ALPP, also known as alkaline phosphatase, placental, is a family of dimeric metalloenzymes catalyzing the hydrolysis of monoesters of phosphoric acid. Also, this protein catalyzes a transphosphorylation reaction in the presence of large concentrations of phosphate acceptors. It occurs widely in nature, and are found in many organisms from Escherichia coli to man. Most alkaline phosphatases are homodimeric enzymes and each catalytic site contains three metal ions (two Zn and one Mg), that are necessary for enzymatic activity. Recombinant human ALPP, fused to His-tag at C-terminus, was expressed in insect cell and purified by using conventional chromatography techniques.