Alkaline Phosphatase - a Mg/Zn Enzyme

The extremely important role that the linkage and hydrolysis of oligophosphates play in nature (a human being daily produces an amount of ATP roughly equivalent to his or her body weight) underlines the importance of phosphatases. Along with the acidic phophatase, which has an iron center, the alkaline phosphatase with a multinuclear magnesium/zinc center plays an important role.


This enzyme consists of two domains, each of which has a prosthetic group. These are each made up of two zinc atoms and a magnesium atom, which are coordinated by histidine, asparagine, glutamine, threonine and serine. Phosphate units coordinate bridging the zinc atoms, which brings them close to a water ligand on the magnesium ion. This leads to an orientation of the phosphate which makes hydrolysis possible.