Essay on A Brief Note On Alkaline Phosphatase ( Ap )

764 Words Mar 3rd, 2016 4 Pages
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 the efficiency of the enzyme while removing Zn ions will result in the loss of catalytic activities (6). However, the importance of Mg ion was first ignored and undefined until it was confirmed by Anderson et al. (11). Mg ion serves as a regulator for the binding of Zn ions to their binding sites and stabilizes the enzyme in its most active form, thus enhancing catalysis.
As denoted by its name, AP possesses optimal catalytic activities in alkaline conditions, but pH may vary among different organisms. The primary functions of alkaline phosphatase involve the hydrolysis and transphosphorylation of phosphomonoester molecules (5). A reaction scheme of AP is presented (Figure 1). The first step of the catalytic reaction occurs when AP…

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